Age Owner Branch data TLA Line data Source code
1 : : /*-------------------------------------------------------------------------
2 : : *
3 : : * verify_nbtree.c
4 : : * Verifies the integrity of nbtree indexes based on invariants.
5 : : *
6 : : * For B-Tree indexes, verification includes checking that each page in the
7 : : * target index has items in logical order as reported by an insertion scankey
8 : : * (the insertion scankey sort-wise NULL semantics are needed for
9 : : * verification).
10 : : *
11 : : * When index-to-heap verification is requested, a Bloom filter is used to
12 : : * fingerprint all tuples in the target index, as the index is traversed to
13 : : * verify its structure. A heap scan later uses Bloom filter probes to verify
14 : : * that every visible heap tuple has a matching index tuple.
15 : : *
16 : : *
17 : : * Copyright (c) 2017-2025, PostgreSQL Global Development Group
18 : : *
19 : : * IDENTIFICATION
20 : : * contrib/amcheck/verify_nbtree.c
21 : : *
22 : : *-------------------------------------------------------------------------
23 : : */
24 : : #include "postgres.h"
25 : :
26 : : #include "access/heaptoast.h"
27 : : #include "access/htup_details.h"
28 : : #include "access/nbtree.h"
29 : : #include "access/table.h"
30 : : #include "access/tableam.h"
31 : : #include "access/transam.h"
32 : : #include "access/xact.h"
33 : : #include "verify_common.h"
34 : : #include "catalog/index.h"
35 : : #include "catalog/pg_am.h"
36 : : #include "catalog/pg_opfamily_d.h"
37 : : #include "common/pg_prng.h"
38 : : #include "lib/bloomfilter.h"
39 : : #include "miscadmin.h"
40 : : #include "storage/smgr.h"
41 : : #include "utils/guc.h"
42 : : #include "utils/memutils.h"
43 : : #include "utils/snapmgr.h"
44 : :
45 : :
265 tgl@sss.pgh.pa.us 46 :CBC 328 : PG_MODULE_MAGIC_EXT(
47 : : .name = "amcheck",
48 : : .version = PG_VERSION
49 : : );
50 : :
51 : : /*
52 : : * A B-Tree cannot possibly have this many levels, since there must be one
53 : : * block per level, which is bound by the range of BlockNumber:
54 : : */
55 : : #define InvalidBtreeLevel ((uint32) InvalidBlockNumber)
56 : : #define BTreeTupleGetNKeyAtts(itup, rel) \
57 : : Min(IndexRelationGetNumberOfKeyAttributes(rel), BTreeTupleGetNAtts(itup, rel))
58 : :
59 : : /*
60 : : * State associated with verifying a B-Tree index
61 : : *
62 : : * target is the point of reference for a verification operation.
63 : : *
64 : : * Other B-Tree pages may be allocated, but those are always auxiliary (e.g.,
65 : : * they are current target's child pages). Conceptually, problems are only
66 : : * ever found in the current target page (or for a particular heap tuple during
67 : : * heapallindexed verification). Each page found by verification's left/right,
68 : : * top/bottom scan becomes the target exactly once.
69 : : */
70 : : typedef struct BtreeCheckState
71 : : {
72 : : /*
73 : : * Unchanging state, established at start of verification:
74 : : */
75 : :
76 : : /* B-Tree Index Relation and associated heap relation */
77 : : Relation rel;
78 : : Relation heaprel;
79 : : /* rel is heapkeyspace index? */
80 : : bool heapkeyspace;
81 : : /* ShareLock held on heap/index, rather than AccessShareLock? */
82 : : bool readonly;
83 : : /* Also verifying heap has no unindexed tuples? */
84 : : bool heapallindexed;
85 : : /* Also making sure non-pivot tuples can be found by new search? */
86 : : bool rootdescend;
87 : : /* Also check uniqueness constraint if index is unique */
88 : : bool checkunique;
89 : : /* Per-page context */
90 : : MemoryContext targetcontext;
91 : : /* Buffer access strategy */
92 : : BufferAccessStrategy checkstrategy;
93 : :
94 : : /*
95 : : * Info for uniqueness checking. Fill these fields once per index check.
96 : : */
97 : : IndexInfo *indexinfo;
98 : : Snapshot snapshot;
99 : :
100 : : /*
101 : : * Mutable state, for verification of particular page:
102 : : */
103 : :
104 : : /* Current target page */
105 : : Page target;
106 : : /* Target block number */
107 : : BlockNumber targetblock;
108 : : /* Target page's LSN */
109 : : XLogRecPtr targetlsn;
110 : :
111 : : /*
112 : : * Low key: high key of left sibling of target page. Used only for child
113 : : * verification. So, 'lowkey' is kept only when 'readonly' is set.
114 : : */
115 : : IndexTuple lowkey;
116 : :
117 : : /*
118 : : * The rightlink and incomplete split flag of block one level down to the
119 : : * target page, which was visited last time via downlink from target page.
120 : : * We use it to check for missing downlinks.
121 : : */
122 : : BlockNumber prevrightlink;
123 : : bool previncompletesplit;
124 : :
125 : : /*
126 : : * Mutable state, for optional heapallindexed verification:
127 : : */
128 : :
129 : : /* Bloom filter fingerprints B-Tree index */
130 : : bloom_filter *filter;
131 : : /* Debug counter */
132 : : int64 heaptuplespresent;
133 : : } BtreeCheckState;
134 : :
135 : : /*
136 : : * Starting point for verifying an entire B-Tree index level
137 : : */
138 : : typedef struct BtreeLevel
139 : : {
140 : : /* Level number (0 is leaf page level). */
141 : : uint32 level;
142 : :
143 : : /* Left most block on level. Scan of level begins here. */
144 : : BlockNumber leftmost;
145 : :
146 : : /* Is this level reported as "true" root level by meta page? */
147 : : bool istruerootlevel;
148 : : } BtreeLevel;
149 : :
150 : : /*
151 : : * Information about the last visible entry with current B-tree key. Used
152 : : * for validation of the unique constraint.
153 : : */
154 : : typedef struct BtreeLastVisibleEntry
155 : : {
156 : : BlockNumber blkno; /* Index block */
157 : : OffsetNumber offset; /* Offset on index block */
158 : : int postingIndex; /* Number in the posting list (-1 for
159 : : * non-deduplicated tuples) */
160 : : ItemPointer tid; /* Heap tid */
161 : : } BtreeLastVisibleEntry;
162 : :
163 : : /*
164 : : * arguments for the bt_index_check_callback callback
165 : : */
166 : : typedef struct BTCallbackState
167 : : {
168 : : bool parentcheck;
169 : : bool heapallindexed;
170 : : bool rootdescend;
171 : : bool checkunique;
172 : : } BTCallbackState;
173 : :
3204 andres@anarazel.de 174 : 93 : PG_FUNCTION_INFO_V1(bt_index_check);
175 : 65 : PG_FUNCTION_INFO_V1(bt_index_parent_check);
176 : :
177 : : static void bt_index_check_callback(Relation indrel, Relation heaprel,
178 : : void *state, bool readonly);
179 : : static void bt_check_every_level(Relation rel, Relation heaprel,
180 : : bool heapkeyspace, bool readonly, bool heapallindexed,
181 : : bool rootdescend, bool checkunique);
182 : : static BtreeLevel bt_check_level_from_leftmost(BtreeCheckState *state,
183 : : BtreeLevel level);
184 : : static bool bt_leftmost_ignoring_half_dead(BtreeCheckState *state,
185 : : BlockNumber start,
186 : : BTPageOpaque start_opaque);
187 : : static void bt_recheck_sibling_links(BtreeCheckState *state,
188 : : BlockNumber btpo_prev_from_target,
189 : : BlockNumber leftcurrent);
190 : : static bool heap_entry_is_visible(BtreeCheckState *state, ItemPointer tid);
191 : : static void bt_report_duplicate(BtreeCheckState *state,
192 : : BtreeLastVisibleEntry *lVis,
193 : : ItemPointer nexttid,
194 : : BlockNumber nblock, OffsetNumber noffset,
195 : : int nposting);
196 : : static void bt_entry_unique_check(BtreeCheckState *state, IndexTuple itup,
197 : : BlockNumber targetblock, OffsetNumber offset,
198 : : BtreeLastVisibleEntry *lVis);
199 : : static void bt_target_page_check(BtreeCheckState *state);
200 : : static BTScanInsert bt_right_page_check_scankey(BtreeCheckState *state,
201 : : OffsetNumber *rightfirstoffset);
202 : : static void bt_child_check(BtreeCheckState *state, BTScanInsert targetkey,
203 : : OffsetNumber downlinkoffnum);
204 : : static void bt_child_highkey_check(BtreeCheckState *state,
205 : : OffsetNumber target_downlinkoffnum,
206 : : Page loaded_child,
207 : : uint32 target_level);
208 : : static void bt_downlink_missing_check(BtreeCheckState *state, bool rightsplit,
209 : : BlockNumber blkno, Page page);
210 : : static void bt_tuple_present_callback(Relation index, ItemPointer tid,
211 : : Datum *values, bool *isnull,
212 : : bool tupleIsAlive, void *checkstate);
213 : : static IndexTuple bt_normalize_tuple(BtreeCheckState *state,
214 : : IndexTuple itup);
215 : : static inline IndexTuple bt_posting_plain_tuple(IndexTuple itup, int n);
216 : : static bool bt_rootdescend(BtreeCheckState *state, IndexTuple itup);
217 : : static inline bool offset_is_negative_infinity(BTPageOpaque opaque,
218 : : OffsetNumber offset);
219 : : static inline bool invariant_l_offset(BtreeCheckState *state, BTScanInsert key,
220 : : OffsetNumber upperbound);
221 : : static inline bool invariant_leq_offset(BtreeCheckState *state,
222 : : BTScanInsert key,
223 : : OffsetNumber upperbound);
224 : : static inline bool invariant_g_offset(BtreeCheckState *state, BTScanInsert key,
225 : : OffsetNumber lowerbound);
226 : : static inline bool invariant_l_nontarget_offset(BtreeCheckState *state,
227 : : BTScanInsert key,
228 : : BlockNumber nontargetblock,
229 : : Page nontarget,
230 : : OffsetNumber upperbound);
231 : : static Page palloc_btree_page(BtreeCheckState *state, BlockNumber blocknum);
232 : : static inline BTScanInsert bt_mkscankey_pivotsearch(Relation rel,
233 : : IndexTuple itup);
234 : : static ItemId PageGetItemIdCareful(BtreeCheckState *state, BlockNumber block,
235 : : Page page, OffsetNumber offset);
236 : : static inline ItemPointer BTreeTupleGetHeapTIDCareful(BtreeCheckState *state,
237 : : IndexTuple itup, bool nonpivot);
238 : : static inline ItemPointer BTreeTupleGetPointsToTID(IndexTuple itup);
239 : :
240 : : /*
241 : : * bt_index_check(index regclass, heapallindexed boolean, checkunique boolean)
242 : : *
243 : : * Verify integrity of B-Tree index.
244 : : *
245 : : * Acquires AccessShareLock on heap & index relations. Does not consider
246 : : * invariants that exist between parent/child pages. Optionally verifies
247 : : * that heap does not contain any unindexed or incorrectly indexed tuples.
248 : : */
249 : : Datum
250 : 3940 : bt_index_check(PG_FUNCTION_ARGS)
251 : : {
252 : 3940 : Oid indrelid = PG_GETARG_OID(0);
253 : : BTCallbackState args;
254 : :
262 tomas.vondra@postgre 255 : 3940 : args.heapallindexed = false;
256 : 3940 : args.rootdescend = false;
257 : 3940 : args.parentcheck = false;
258 : 3940 : args.checkunique = false;
259 : :
780 akorotkov@postgresql 260 [ + + ]: 3940 : if (PG_NARGS() >= 2)
262 tomas.vondra@postgre 261 : 3934 : args.heapallindexed = PG_GETARG_BOOL(1);
262 [ + + ]: 3940 : if (PG_NARGS() >= 3)
263 : 682 : args.checkunique = PG_GETARG_BOOL(2);
264 : :
265 : 3940 : amcheck_lock_relation_and_check(indrelid, BTREE_AM_OID,
266 : : bt_index_check_callback,
267 : : AccessShareLock, &args);
268 : :
3204 andres@anarazel.de 269 : 3914 : PG_RETURN_VOID();
270 : : }
271 : :
272 : : /*
273 : : * bt_index_parent_check(index regclass, heapallindexed boolean, rootdescend boolean, checkunique boolean)
274 : : *
275 : : * Verify integrity of B-Tree index.
276 : : *
277 : : * Acquires ShareLock on heap & index relations. Verifies that downlinks in
278 : : * parent pages are valid lower bounds on child pages. Optionally verifies
279 : : * that heap does not contain any unindexed or incorrectly indexed tuples.
280 : : */
281 : : Datum
282 : 62 : bt_index_parent_check(PG_FUNCTION_ARGS)
283 : : {
284 : 62 : Oid indrelid = PG_GETARG_OID(0);
285 : : BTCallbackState args;
286 : :
262 tomas.vondra@postgre 287 : 62 : args.heapallindexed = false;
288 : 62 : args.rootdescend = false;
289 : 62 : args.parentcheck = true;
290 : 62 : args.checkunique = false;
291 : :
2463 pg@bowt.ie 292 [ + + ]: 62 : if (PG_NARGS() >= 2)
262 tomas.vondra@postgre 293 : 56 : args.heapallindexed = PG_GETARG_BOOL(1);
780 akorotkov@postgresql 294 [ + + ]: 62 : if (PG_NARGS() >= 3)
262 tomas.vondra@postgre 295 : 52 : args.rootdescend = PG_GETARG_BOOL(2);
296 [ + + ]: 62 : if (PG_NARGS() >= 4)
297 : 26 : args.checkunique = PG_GETARG_BOOL(3);
298 : :
299 : 62 : amcheck_lock_relation_and_check(indrelid, BTREE_AM_OID,
300 : : bt_index_check_callback,
301 : : ShareLock, &args);
302 : :
3204 andres@anarazel.de 303 : 44 : PG_RETURN_VOID();
304 : : }
305 : :
306 : : /*
307 : : * Helper for bt_index_[parent_]check, coordinating the bulk of the work.
308 : : */
309 : : static void
262 tomas.vondra@postgre 310 : 3996 : bt_index_check_callback(Relation indrel, Relation heaprel, void *state, bool readonly)
311 : : {
312 : 3996 : BTCallbackState *args = (BTCallbackState *) state;
313 : : bool heapkeyspace,
314 : : allequalimage;
315 : :
316 [ + + ]: 3996 : if (!smgrexists(RelationGetSmgr(indrel), MAIN_FORKNUM))
3204 andres@anarazel.de 317 [ + - ]: 18 : ereport(ERROR,
318 : : (errcode(ERRCODE_INDEX_CORRUPTED),
319 : : errmsg("index \"%s\" lacks a main relation fork",
320 : : RelationGetRelationName(indrel))));
321 : :
322 : : /* Extract metadata from metapage, and sanitize it in passing */
262 tomas.vondra@postgre 323 : 3978 : _bt_metaversion(indrel, &heapkeyspace, &allequalimage);
324 [ + + - + ]: 3978 : if (allequalimage && !heapkeyspace)
262 tomas.vondra@postgre 325 [ # # ]:UBC 0 : ereport(ERROR,
326 : : (errcode(ERRCODE_INDEX_CORRUPTED),
327 : : errmsg("index \"%s\" metapage has equalimage field set on unsupported nbtree version",
328 : : RelationGetRelationName(indrel))));
262 tomas.vondra@postgre 329 [ + + - + ]:CBC 3978 : if (allequalimage && !_bt_allequalimage(indrel, false))
330 : : {
262 tomas.vondra@postgre 331 :UBC 0 : bool has_interval_ops = false;
332 : :
333 [ # # ]: 0 : for (int i = 0; i < IndexRelationGetNumberOfKeyAttributes(indrel); i++)
334 [ # # ]: 0 : if (indrel->rd_opfamily[i] == INTERVAL_BTREE_FAM_OID)
335 : : {
336 : 0 : has_interval_ops = true;
337 [ # # # # ]: 0 : ereport(ERROR,
338 : : (errcode(ERRCODE_INDEX_CORRUPTED),
339 : : errmsg("index \"%s\" metapage incorrectly indicates that deduplication is safe",
340 : : RelationGetRelationName(indrel)),
341 : : has_interval_ops
342 : : ? errhint("This is known of \"interval\" indexes last built on a version predating 2023-11.")
343 : : : 0));
344 : : }
345 : : }
346 : :
347 : : /* Check index, possibly against table it is an index on */
262 tomas.vondra@postgre 348 :CBC 3978 : bt_check_every_level(indrel, heaprel, heapkeyspace, readonly,
349 : 3978 : args->heapallindexed, args->rootdescend, args->checkunique);
2318 pg@bowt.ie 350 : 3958 : }
351 : :
352 : : /*
353 : : * Main entry point for B-Tree SQL-callable functions. Walks the B-Tree in
354 : : * logical order, verifying invariants as it goes. Optionally, verification
355 : : * checks if the heap relation contains any tuples that are not represented in
356 : : * the index but should be.
357 : : *
358 : : * It is the caller's responsibility to acquire appropriate heavyweight lock on
359 : : * the index relation, and advise us if extra checks are safe when a ShareLock
360 : : * is held. (A lock of the same type must also have been acquired on the heap
361 : : * relation.)
362 : : *
363 : : * A ShareLock is generally assumed to prevent any kind of physical
364 : : * modification to the index structure, including modifications that VACUUM may
365 : : * make. This does not include setting of the LP_DEAD bit by concurrent index
366 : : * scans, although that is just metadata that is not able to directly affect
367 : : * any check performed here. Any concurrent process that might act on the
368 : : * LP_DEAD bit being set (recycle space) requires a heavyweight lock that
369 : : * cannot be held while we hold a ShareLock. (Besides, even if that could
370 : : * happen, the ad-hoc recycling when a page might otherwise split is performed
371 : : * per-page, and requires an exclusive buffer lock, which wouldn't cause us
372 : : * trouble. _bt_delitems_vacuum() may only delete leaf items, and so the extra
373 : : * parent/child check cannot be affected.)
374 : : */
375 : : static void
2463 376 : 3978 : bt_check_every_level(Relation rel, Relation heaprel, bool heapkeyspace,
377 : : bool readonly, bool heapallindexed, bool rootdescend,
378 : : bool checkunique)
379 : : {
380 : : BtreeCheckState *state;
381 : : Page metapage;
382 : : BTMetaPageData *metad;
383 : : uint32 previouslevel;
384 : : BtreeLevel current;
385 : :
2076 386 [ + + ]: 3978 : if (!readonly)
387 [ + + ]: 3928 : elog(DEBUG1, "verifying consistency of tree structure for index \"%s\"",
388 : : RelationGetRelationName(rel));
389 : : else
390 [ + + ]: 50 : elog(DEBUG1, "verifying consistency of tree structure for index \"%s\" with cross-level checks",
391 : : RelationGetRelationName(rel));
392 : :
393 : : /*
394 : : * This assertion matches the one in index_getnext_tid(). See page
395 : : * recycling/"visible to everyone" notes in nbtree README.
396 : : */
1952 andres@anarazel.de 397 [ - + ]: 3978 : Assert(TransactionIdIsValid(RecentXmin));
398 : :
399 : : /*
400 : : * Initialize state for entire verification operation
401 : : */
11 michael@paquier.xyz 402 :GNC 3978 : state = palloc0_object(BtreeCheckState);
3204 andres@anarazel.de 403 :CBC 3978 : state->rel = rel;
2817 404 : 3978 : state->heaprel = heaprel;
2463 pg@bowt.ie 405 : 3978 : state->heapkeyspace = heapkeyspace;
3204 andres@anarazel.de 406 : 3978 : state->readonly = readonly;
2817 407 : 3978 : state->heapallindexed = heapallindexed;
2463 pg@bowt.ie 408 : 3978 : state->rootdescend = rootdescend;
780 akorotkov@postgresql 409 : 3978 : state->checkunique = checkunique;
410 : 3978 : state->snapshot = InvalidSnapshot;
411 : :
2817 andres@anarazel.de 412 [ + + ]: 3978 : if (state->heapallindexed)
413 : : {
414 : : int64 total_pages;
415 : : int64 total_elems;
416 : : uint64 seed;
417 : :
418 : : /*
419 : : * Size Bloom filter based on estimated number of tuples in index,
420 : : * while conservatively assuming that each block must contain at least
421 : : * MaxTIDsPerBTreePage / 3 "plain" tuples -- see
422 : : * bt_posting_plain_tuple() for definition, and details of how posting
423 : : * list tuples are handled.
424 : : */
2341 pg@bowt.ie 425 : 77 : total_pages = RelationGetNumberOfBlocks(rel);
2120 426 : 77 : total_elems = Max(total_pages * (MaxTIDsPerBTreePage / 3),
427 : : (int64) state->rel->rd_rel->reltuples);
428 : : /* Generate a random seed to avoid repetition */
1479 tgl@sss.pgh.pa.us 429 : 77 : seed = pg_prng_uint64(&pg_global_prng_state);
430 : : /* Create Bloom filter to fingerprint index */
2817 andres@anarazel.de 431 : 77 : state->filter = bloom_create(total_elems, maintenance_work_mem, seed);
432 : 77 : state->heaptuplespresent = 0;
433 : :
434 : : /*
435 : : * Register our own snapshot for heapallindexed, rather than asking
436 : : * table_index_build_scan() to do this for us later. This needs to
437 : : * happen before index fingerprinting begins, so we can later be
438 : : * certain that index fingerprinting should have reached all tuples
439 : : * returned by table_index_build_scan().
440 : : */
12 alvherre@kurilemu.de 441 : 77 : state->snapshot = RegisterSnapshot(GetTransactionSnapshot());
442 : :
443 : : /*
444 : : * GetTransactionSnapshot() always acquires a new MVCC snapshot in
445 : : * READ COMMITTED mode. A new snapshot is guaranteed to have all the
446 : : * entries it requires in the index.
447 : : *
448 : : * We must defend against the possibility that an old xact snapshot
449 : : * was returned at higher isolation levels when that snapshot is not
450 : : * safe for index scans of the target index. This is possible when
451 : : * the snapshot sees tuples that are before the index's indcheckxmin
452 : : * horizon. Throwing an error here should be very rare. It doesn't
453 : : * seem worth using a secondary snapshot to avoid this.
454 : : */
455 [ - + - - ]: 77 : if (IsolationUsesXactSnapshot() && rel->rd_index->indcheckxmin &&
12 alvherre@kurilemu.de 456 [ # # ]:UBC 0 : !TransactionIdPrecedes(HeapTupleHeaderGetXmin(rel->rd_indextuple->t_data),
457 : 0 : state->snapshot->xmin))
458 [ # # ]: 0 : ereport(ERROR,
459 : : errcode(ERRCODE_T_R_SERIALIZATION_FAILURE),
460 : : errmsg("index \"%s\" cannot be verified using transaction snapshot",
461 : : RelationGetRelationName(rel)));
462 : : }
463 : :
464 : : /*
465 : : * We need a snapshot to check the uniqueness of the index. For better
466 : : * performance, take it once per index check. If one was already taken
467 : : * above, use that.
468 : : */
780 akorotkov@postgresql 469 [ + + ]:CBC 3978 : if (state->checkunique)
470 : : {
471 : 704 : state->indexinfo = BuildIndexInfo(state->rel);
472 : :
12 alvherre@kurilemu.de 473 [ + + + + ]: 704 : if (state->indexinfo->ii_Unique && state->snapshot == InvalidSnapshot)
474 : 621 : state->snapshot = RegisterSnapshot(GetTransactionSnapshot());
475 : : }
476 : :
2463 pg@bowt.ie 477 [ + + - + ]: 3978 : Assert(!state->rootdescend || state->readonly);
478 [ + + - + ]: 3978 : if (state->rootdescend && !state->heapkeyspace)
2463 pg@bowt.ie 479 [ # # ]:UBC 0 : ereport(ERROR,
480 : : (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
481 : : errmsg("cannot verify that tuples from index \"%s\" can each be found by an independent index search",
482 : : RelationGetRelationName(rel)),
483 : : errhint("Only B-Tree version 4 indexes support rootdescend verification.")));
484 : :
485 : : /* Create context for page */
3204 andres@anarazel.de 486 :CBC 3978 : state->targetcontext = AllocSetContextCreate(CurrentMemoryContext,
487 : : "amcheck context",
488 : : ALLOCSET_DEFAULT_SIZES);
489 : 3978 : state->checkstrategy = GetAccessStrategy(BAS_BULKREAD);
490 : :
491 : : /* Get true root block from meta-page */
492 : 3978 : metapage = palloc_btree_page(state, BTREE_METAPAGE);
493 : 3978 : metad = BTPageGetMeta(metapage);
494 : :
495 : : /*
496 : : * Certain deletion patterns can result in "skinny" B-Tree indexes, where
497 : : * the fast root and true root differ.
498 : : *
499 : : * Start from the true root, not the fast root, unlike conventional index
500 : : * scans. This approach is more thorough, and removes the risk of
501 : : * following a stale fast root from the meta page.
502 : : */
503 [ + + ]: 3978 : if (metad->btm_fastroot != metad->btm_root)
504 [ - + ]: 13 : ereport(DEBUG1,
505 : : (errcode(ERRCODE_NO_DATA),
506 : : errmsg_internal("harmless fast root mismatch in index \"%s\"",
507 : : RelationGetRelationName(rel)),
508 : : errdetail_internal("Fast root block %u (level %u) differs from true root block %u (level %u).",
509 : : metad->btm_fastroot, metad->btm_fastlevel,
510 : : metad->btm_root, metad->btm_level)));
511 : :
512 : : /*
513 : : * Starting at the root, verify every level. Move left to right, top to
514 : : * bottom. Note that there may be no pages other than the meta page (meta
515 : : * page can indicate that root is P_NONE when the index is totally empty).
516 : : */
517 : 3978 : previouslevel = InvalidBtreeLevel;
518 : 3978 : current.level = metad->btm_level;
519 : 3978 : current.leftmost = metad->btm_root;
520 : 3978 : current.istruerootlevel = true;
521 [ + + ]: 6473 : while (current.leftmost != P_NONE)
522 : : {
523 : : /*
524 : : * Verify this level, and get left most page for next level down, if
525 : : * not at leaf level
526 : : */
527 : 2513 : current = bt_check_level_from_leftmost(state, current);
528 : :
529 [ - + ]: 2495 : if (current.leftmost == InvalidBlockNumber)
3204 andres@anarazel.de 530 [ # # ]:UBC 0 : ereport(ERROR,
531 : : (errcode(ERRCODE_INDEX_CORRUPTED),
532 : : errmsg("index \"%s\" has no valid pages on level below %u or first level",
533 : : RelationGetRelationName(rel), previouslevel)));
534 : :
3204 andres@anarazel.de 535 :CBC 2495 : previouslevel = current.level;
536 : : }
537 : :
538 : : /*
539 : : * * Check whether heap contains unindexed/malformed tuples *
540 : : */
2817 541 [ + + ]: 3960 : if (state->heapallindexed)
542 : : {
543 : 70 : IndexInfo *indexinfo = BuildIndexInfo(state->rel);
544 : : TableScanDesc scan;
545 : :
546 : : /*
547 : : * Create our own scan for table_index_build_scan(), rather than
548 : : * getting it to do so for us. This is required so that we can
549 : : * actually use the MVCC snapshot registered earlier.
550 : : *
551 : : * Note that table_index_build_scan() calls heap_endscan() for us.
552 : : */
2456 553 : 70 : scan = table_beginscan_strat(state->heaprel, /* relation */
554 : : state->snapshot, /* snapshot */
555 : : 0, /* number of keys */
556 : : NULL, /* scan key */
557 : : true, /* buffer access strategy OK */
558 : : true); /* syncscan OK? */
559 : :
560 : : /*
561 : : * Scan will behave as the first scan of a CREATE INDEX CONCURRENTLY
562 : : * behaves.
563 : : *
564 : : * It's okay that we don't actually use the same lock strength for the
565 : : * heap relation as any other ii_Concurrent caller would. We have no
566 : : * reason to care about a concurrent VACUUM operation, since there
567 : : * isn't going to be a second scan of the heap that needs to be sure
568 : : * that there was no concurrent recycling of TIDs.
569 : : */
12 alvherre@kurilemu.de 570 : 68 : indexinfo->ii_Concurrent = true;
571 : :
572 : : /*
573 : : * Don't wait for uncommitted tuple xact commit/abort when index is a
574 : : * unique index on a catalog (or an index used by an exclusion
575 : : * constraint). This could otherwise happen in the readonly case.
576 : : */
2817 andres@anarazel.de 577 : 68 : indexinfo->ii_Unique = false;
578 : 68 : indexinfo->ii_ExclusionOps = NULL;
579 : 68 : indexinfo->ii_ExclusionProcs = NULL;
580 : 68 : indexinfo->ii_ExclusionStrats = NULL;
581 : :
582 [ + + ]: 68 : elog(DEBUG1, "verifying that tuples from index \"%s\" are present in \"%s\"",
583 : : RelationGetRelationName(state->rel),
584 : : RelationGetRelationName(state->heaprel));
585 : :
2450 alvherre@alvh.no-ip. 586 : 68 : table_index_build_scan(state->heaprel, state->rel, indexinfo, true, false,
587 : : bt_tuple_present_callback, state, scan);
588 : :
2817 andres@anarazel.de 589 [ + + ]: 68 : ereport(DEBUG1,
590 : : (errmsg_internal("finished verifying presence of " INT64_FORMAT " tuples from table \"%s\" with bitset %.2f%% set",
591 : : state->heaptuplespresent, RelationGetRelationName(heaprel),
592 : : 100.0 * bloom_prop_bits_set(state->filter))));
593 : :
594 : 68 : bloom_free(state->filter);
595 : : }
596 : :
597 : : /* Be tidy: */
12 alvherre@kurilemu.de 598 [ + + ]: 3958 : if (state->snapshot != InvalidSnapshot)
780 akorotkov@postgresql 599 : 689 : UnregisterSnapshot(state->snapshot);
3204 andres@anarazel.de 600 : 3958 : MemoryContextDelete(state->targetcontext);
601 : 3958 : }
602 : :
603 : : /*
604 : : * Given a left-most block at some level, move right, verifying each page
605 : : * individually (with more verification across pages for "readonly"
606 : : * callers). Caller should pass the true root page as the leftmost initially,
607 : : * working their way down by passing what is returned for the last call here
608 : : * until level 0 (leaf page level) was reached.
609 : : *
610 : : * Returns state for next call, if any. This includes left-most block number
611 : : * one level lower that should be passed on next level/call, which is set to
612 : : * P_NONE on last call here (when leaf level is verified). Level numbers
613 : : * follow the nbtree convention: higher levels have higher numbers, because new
614 : : * levels are added only due to a root page split. Note that prior to the
615 : : * first root page split, the root is also a leaf page, so there is always a
616 : : * level 0 (leaf level), and it's always the last level processed.
617 : : *
618 : : * Note on memory management: State's per-page context is reset here, between
619 : : * each call to bt_target_page_check().
620 : : */
621 : : static BtreeLevel
622 : 2513 : bt_check_level_from_leftmost(BtreeCheckState *state, BtreeLevel level)
623 : : {
624 : : /* State to establish early, concerning entire level */
625 : : BTPageOpaque opaque;
626 : : MemoryContext oldcontext;
627 : : BtreeLevel nextleveldown;
628 : :
629 : : /* Variables for iterating across level using right links */
630 : 2513 : BlockNumber leftcurrent = P_NONE;
631 : 2513 : BlockNumber current = level.leftmost;
632 : :
633 : : /* Initialize return state */
634 : 2513 : nextleveldown.leftmost = InvalidBlockNumber;
635 : 2513 : nextleveldown.level = InvalidBtreeLevel;
636 : 2513 : nextleveldown.istruerootlevel = false;
637 : :
638 : : /* Use page-level context for duration of this call */
639 : 2513 : oldcontext = MemoryContextSwitchTo(state->targetcontext);
640 : :
2076 pg@bowt.ie 641 [ + + + + : 2513 : elog(DEBUG1, "verifying level %u%s", level.level,
+ - ]
642 : : level.istruerootlevel ?
643 : : " (true root level)" : level.level == 0 ? " (leaf level)" : "");
644 : :
2106 akorotkov@postgresql 645 : 2513 : state->prevrightlink = InvalidBlockNumber;
646 : 2513 : state->previncompletesplit = false;
647 : :
648 : : do
649 : : {
650 : : /* Don't rely on CHECK_FOR_INTERRUPTS() calls at lower level */
3204 andres@anarazel.de 651 [ - + ]: 9316 : CHECK_FOR_INTERRUPTS();
652 : :
653 : : /* Initialize state for this iteration */
654 : 9316 : state->targetblock = current;
655 : 9316 : state->target = palloc_btree_page(state, state->targetblock);
656 : 9304 : state->targetlsn = PageGetLSN(state->target);
657 : :
1355 michael@paquier.xyz 658 : 9304 : opaque = BTPageGetOpaque(state->target);
659 : :
3204 andres@anarazel.de 660 [ - + ]: 9304 : if (P_IGNORE(opaque))
661 : : {
662 : : /*
663 : : * Since there cannot be a concurrent VACUUM operation in readonly
664 : : * mode, and since a page has no links within other pages
665 : : * (siblings and parent) once it is marked fully deleted, it
666 : : * should be impossible to land on a fully deleted page in
667 : : * readonly mode. See bt_child_check() for further details.
668 : : *
669 : : * The bt_child_check() P_ISDELETED() check is repeated here so
670 : : * that pages that are only reachable through sibling links get
671 : : * checked.
672 : : */
2792 teodor@sigaev.ru 673 [ # # # # ]:UBC 0 : if (state->readonly && P_ISDELETED(opaque))
674 [ # # ]: 0 : ereport(ERROR,
675 : : (errcode(ERRCODE_INDEX_CORRUPTED),
676 : : errmsg("downlink or sibling link points to deleted block in index \"%s\"",
677 : : RelationGetRelationName(state->rel)),
678 : : errdetail_internal("Block=%u left block=%u left link from block=%u.",
679 : : current, leftcurrent, opaque->btpo_prev)));
680 : :
3204 andres@anarazel.de 681 [ # # ]: 0 : if (P_RIGHTMOST(opaque))
682 [ # # ]: 0 : ereport(ERROR,
683 : : (errcode(ERRCODE_INDEX_CORRUPTED),
684 : : errmsg("block %u fell off the end of index \"%s\"",
685 : : current, RelationGetRelationName(state->rel))));
686 : : else
687 [ # # ]: 0 : ereport(DEBUG1,
688 : : (errcode(ERRCODE_NO_DATA),
689 : : errmsg_internal("block %u of index \"%s\" concurrently deleted",
690 : : current, RelationGetRelationName(state->rel))));
691 : 0 : goto nextpage;
692 : : }
3204 andres@anarazel.de 693 [ + + ]:CBC 9304 : else if (nextleveldown.leftmost == InvalidBlockNumber)
694 : : {
695 : : /*
696 : : * A concurrent page split could make the caller supplied leftmost
697 : : * block no longer contain the leftmost page, or no longer be the
698 : : * true root, but where that isn't possible due to heavyweight
699 : : * locking, check that the first valid page meets caller's
700 : : * expectations.
701 : : */
702 [ + + ]: 2501 : if (state->readonly)
703 : : {
778 noah@leadboat.com 704 [ - + ]: 45 : if (!bt_leftmost_ignoring_half_dead(state, current, opaque))
3204 andres@anarazel.de 705 [ # # ]:UBC 0 : ereport(ERROR,
706 : : (errcode(ERRCODE_INDEX_CORRUPTED),
707 : : errmsg("block %u is not leftmost in index \"%s\"",
708 : : current, RelationGetRelationName(state->rel))));
709 : :
14 heikki.linnakangas@i 710 [ + + - + :CBC 45 : if (level.istruerootlevel && (!P_ISROOT(opaque) && !P_INCOMPLETE_SPLIT(opaque)))
- - ]
3204 andres@anarazel.de 711 [ # # ]:UBC 0 : ereport(ERROR,
712 : : (errcode(ERRCODE_INDEX_CORRUPTED),
713 : : errmsg("block %u is not true root in index \"%s\"",
714 : : current, RelationGetRelationName(state->rel))));
715 : : }
716 : :
717 : : /*
718 : : * Before beginning any non-trivial examination of level, prepare
719 : : * state for next bt_check_level_from_leftmost() invocation for
720 : : * the next level for the next level down (if any).
721 : : *
722 : : * There should be at least one non-ignorable page per level,
723 : : * unless this is the leaf level, which is assumed by caller to be
724 : : * final level.
725 : : */
3204 andres@anarazel.de 726 [ + + ]:CBC 2501 : if (!P_ISLEAF(opaque))
727 : : {
728 : : IndexTuple itup;
729 : : ItemId itemid;
730 : :
731 : : /* Internal page -- downlink gets leftmost on next level */
2427 pg@bowt.ie 732 : 555 : itemid = PageGetItemIdCareful(state, state->targetblock,
733 : : state->target,
734 [ + + ]: 555 : P_FIRSTDATAKEY(opaque));
3204 andres@anarazel.de 735 : 555 : itup = (IndexTuple) PageGetItem(state->target, itemid);
2192 pg@bowt.ie 736 : 555 : nextleveldown.leftmost = BTreeTupleGetDownLink(itup);
1756 737 : 555 : nextleveldown.level = opaque->btpo_level - 1;
738 : : }
739 : : else
740 : : {
741 : : /*
742 : : * Leaf page -- final level caller must process.
743 : : *
744 : : * Note that this could also be the root page, if there has
745 : : * been no root page split yet.
746 : : */
3204 andres@anarazel.de 747 : 1946 : nextleveldown.leftmost = P_NONE;
748 : 1946 : nextleveldown.level = InvalidBtreeLevel;
749 : : }
750 : :
751 : : /*
752 : : * Finished setting up state for this call/level. Control will
753 : : * never end up back here in any future loop iteration for this
754 : : * level.
755 : : */
756 : : }
757 : :
758 : : /*
759 : : * Sibling links should be in mutual agreement. There arises
760 : : * leftcurrent == P_NONE && btpo_prev != P_NONE when the left sibling
761 : : * of the parent's low-key downlink is half-dead. (A half-dead page
762 : : * has no downlink from its parent.) Under heavyweight locking, the
763 : : * last bt_leftmost_ignoring_half_dead() validated this btpo_prev.
764 : : * Without heavyweight locking, validation of the P_NONE case remains
765 : : * unimplemented.
766 : : */
778 noah@leadboat.com 767 [ + + - + ]: 9304 : if (opaque->btpo_prev != leftcurrent && leftcurrent != P_NONE)
1956 pg@bowt.ie 768 :UBC 0 : bt_recheck_sibling_links(state, opaque->btpo_prev, leftcurrent);
769 : :
770 : : /* Check level */
1756 pg@bowt.ie 771 [ - + ]:CBC 9304 : if (level.level != opaque->btpo_level)
3204 andres@anarazel.de 772 [ # # ]:UBC 0 : ereport(ERROR,
773 : : (errcode(ERRCODE_INDEX_CORRUPTED),
774 : : errmsg("leftmost down link for level points to block in index \"%s\" whose level is not one level down",
775 : : RelationGetRelationName(state->rel)),
776 : : errdetail_internal("Block pointed to=%u expected level=%u level in pointed to block=%u.",
777 : : current, level.level, opaque->btpo_level)));
778 : :
779 : : /* Verify invariants for page */
3204 andres@anarazel.de 780 :CBC 9304 : bt_target_page_check(state);
781 : :
782 : 9298 : nextpage:
783 : :
784 : : /* Try to detect circular links */
785 [ + - - + ]: 9298 : if (current == leftcurrent || current == opaque->btpo_prev)
3204 andres@anarazel.de 786 [ # # ]:UBC 0 : ereport(ERROR,
787 : : (errcode(ERRCODE_INDEX_CORRUPTED),
788 : : errmsg("circular link chain found in block %u of index \"%s\"",
789 : : current, RelationGetRelationName(state->rel))));
790 : :
2106 akorotkov@postgresql 791 :CBC 9298 : leftcurrent = current;
792 : 9298 : current = opaque->btpo_next;
793 : :
794 [ + + ]: 9298 : if (state->lowkey)
795 : : {
796 [ - + ]: 1862 : Assert(state->readonly);
797 : 1862 : pfree(state->lowkey);
798 : 1862 : state->lowkey = NULL;
799 : : }
800 : :
801 : : /*
802 : : * Copy current target high key as the low key of right sibling.
803 : : * Allocate memory in upper level context, so it would be cleared
804 : : * after reset of target context.
805 : : *
806 : : * We only need the low key in corner cases of checking child high
807 : : * keys. We use high key only when incomplete split on the child level
808 : : * falls to the boundary of pages on the target level. See
809 : : * bt_child_highkey_check() for details. So, typically we won't end
810 : : * up doing anything with low key, but it's simpler for general case
811 : : * high key verification to always have it available.
812 : : *
813 : : * The correctness of managing low key in the case of concurrent
814 : : * splits wasn't investigated yet. Thankfully we only need low key
815 : : * for readonly verification and concurrent splits won't happen.
816 : : */
817 [ + + + + ]: 9298 : if (state->readonly && !P_RIGHTMOST(opaque))
818 : : {
819 : : IndexTuple itup;
820 : : ItemId itemid;
821 : :
822 : 1862 : itemid = PageGetItemIdCareful(state, state->targetblock,
823 : : state->target, P_HIKEY);
824 : 1862 : itup = (IndexTuple) PageGetItem(state->target, itemid);
825 : :
826 : 1862 : state->lowkey = MemoryContextAlloc(oldcontext, IndexTupleSize(itup));
827 : 1862 : memcpy(state->lowkey, itup, IndexTupleSize(itup));
828 : : }
829 : :
830 : : /* Free page and associated memory for this iteration */
3204 andres@anarazel.de 831 : 9298 : MemoryContextReset(state->targetcontext);
832 : : }
833 [ + + ]: 9298 : while (current != P_NONE);
834 : :
2106 akorotkov@postgresql 835 [ - + ]: 2495 : if (state->lowkey)
836 : : {
2106 akorotkov@postgresql 837 [ # # ]:UBC 0 : Assert(state->readonly);
838 : 0 : pfree(state->lowkey);
839 : 0 : state->lowkey = NULL;
840 : : }
841 : :
842 : : /* Don't change context for caller */
3204 andres@anarazel.de 843 :CBC 2495 : MemoryContextSwitchTo(oldcontext);
844 : :
845 : 2495 : return nextleveldown;
846 : : }
847 : :
848 : : /* Check visibility of the table entry referenced by nbtree index */
849 : : static bool
780 akorotkov@postgresql 850 : 387 : heap_entry_is_visible(BtreeCheckState *state, ItemPointer tid)
851 : : {
852 : : bool tid_visible;
853 : :
854 : 387 : TupleTableSlot *slot = table_slot_create(state->heaprel, NULL);
855 : :
856 : 387 : tid_visible = table_tuple_fetch_row_version(state->heaprel,
857 : : tid, state->snapshot, slot);
858 [ + - ]: 387 : if (slot != NULL)
859 : 387 : ExecDropSingleTupleTableSlot(slot);
860 : :
861 : 387 : return tid_visible;
862 : : }
863 : :
864 : : /*
865 : : * Prepare an error message for unique constrain violation in
866 : : * a btree index and report ERROR.
867 : : */
868 : : static void
869 : 3 : bt_report_duplicate(BtreeCheckState *state,
870 : : BtreeLastVisibleEntry *lVis,
871 : : ItemPointer nexttid, BlockNumber nblock, OffsetNumber noffset,
872 : : int nposting)
873 : : {
874 : : char *htid,
875 : : *nhtid,
876 : : *itid,
877 : 3 : *nitid = "",
878 : 3 : *pposting = "",
879 : 3 : *pnposting = "";
880 : :
881 : 3 : htid = psprintf("tid=(%u,%u)",
572 882 : 3 : ItemPointerGetBlockNumberNoCheck(lVis->tid),
883 : 3 : ItemPointerGetOffsetNumberNoCheck(lVis->tid));
780 884 : 3 : nhtid = psprintf("tid=(%u,%u)",
885 : : ItemPointerGetBlockNumberNoCheck(nexttid),
886 : 3 : ItemPointerGetOffsetNumberNoCheck(nexttid));
572 887 : 3 : itid = psprintf("tid=(%u,%u)", lVis->blkno, lVis->offset);
888 : :
889 [ + - + - ]: 3 : if (nblock != lVis->blkno || noffset != lVis->offset)
780 890 : 3 : nitid = psprintf(" tid=(%u,%u)", nblock, noffset);
891 : :
572 892 [ - + ]: 3 : if (lVis->postingIndex >= 0)
572 akorotkov@postgresql 893 :UBC 0 : pposting = psprintf(" posting %u", lVis->postingIndex);
894 : :
780 akorotkov@postgresql 895 [ - + ]:CBC 3 : if (nposting >= 0)
780 akorotkov@postgresql 896 :UBC 0 : pnposting = psprintf(" posting %u", nposting);
897 : :
780 akorotkov@postgresql 898 [ + - ]:CBC 3 : ereport(ERROR,
899 : : (errcode(ERRCODE_INDEX_CORRUPTED),
900 : : errmsg("index uniqueness is violated for index \"%s\"",
901 : : RelationGetRelationName(state->rel)),
902 : : errdetail("Index %s%s and%s%s (point to heap %s and %s) page lsn=%X/%08X.",
903 : : itid, pposting, nitid, pnposting, htid, nhtid,
904 : : LSN_FORMAT_ARGS(state->targetlsn))));
905 : : }
906 : :
907 : : /* Check if current nbtree leaf entry complies with UNIQUE constraint */
908 : : static void
909 : 371 : bt_entry_unique_check(BtreeCheckState *state, IndexTuple itup,
910 : : BlockNumber targetblock, OffsetNumber offset,
911 : : BtreeLastVisibleEntry *lVis)
912 : : {
913 : : ItemPointer tid;
914 : 371 : bool has_visible_entry = false;
915 : :
916 [ - + ]: 371 : Assert(targetblock != P_NONE);
917 : :
918 : : /*
919 : : * Current tuple has posting list. Report duplicate if TID of any posting
920 : : * list entry is visible and lVis->tid is valid.
921 : : */
922 [ + + ]: 371 : if (BTreeTupleIsPosting(itup))
923 : : {
780 akorotkov@postgresql 924 [ + + ]:GBC 48 : for (int i = 0; i < BTreeTupleGetNPosting(itup); i++)
925 : : {
926 : 32 : tid = BTreeTupleGetPostingN(itup, i);
927 [ + + ]: 32 : if (heap_entry_is_visible(state, tid))
928 : : {
929 : 16 : has_visible_entry = true;
572 930 [ - + ]: 16 : if (ItemPointerIsValid(lVis->tid))
931 : : {
780 akorotkov@postgresql 932 :UBC 0 : bt_report_duplicate(state,
933 : : lVis,
934 : : tid, targetblock,
935 : : offset, i);
936 : : }
937 : :
938 : : /*
939 : : * Prevent double reporting unique constraint violation
940 : : * between the posting list entries of the first tuple on the
941 : : * page after cross-page check.
942 : : */
572 akorotkov@postgresql 943 [ + - - + ]:GBC 16 : if (lVis->blkno != targetblock && ItemPointerIsValid(lVis->tid))
780 akorotkov@postgresql 944 :UBC 0 : return;
945 : :
572 akorotkov@postgresql 946 :GBC 16 : lVis->blkno = targetblock;
947 : 16 : lVis->offset = offset;
948 : 16 : lVis->postingIndex = i;
949 : 16 : lVis->tid = tid;
950 : : }
951 : : }
952 : : }
953 : :
954 : : /*
955 : : * Current tuple has no posting list. If TID is visible save info about it
956 : : * for the next comparisons in the loop in bt_target_page_check(). Report
957 : : * duplicate if lVis->tid is already valid.
958 : : */
959 : : else
960 : : {
780 akorotkov@postgresql 961 :CBC 355 : tid = BTreeTupleGetHeapTID(itup);
962 [ + + ]: 355 : if (heap_entry_is_visible(state, tid))
963 : : {
964 : 15 : has_visible_entry = true;
572 965 [ + + ]: 15 : if (ItemPointerIsValid(lVis->tid))
966 : : {
780 967 : 3 : bt_report_duplicate(state,
968 : : lVis,
969 : : tid, targetblock,
970 : : offset, -1);
971 : : }
972 : :
572 973 : 12 : lVis->blkno = targetblock;
974 : 12 : lVis->offset = offset;
975 : 12 : lVis->tid = tid;
976 : 12 : lVis->postingIndex = -1;
977 : : }
978 : : }
979 : :
980 [ + + ]: 368 : if (!has_visible_entry &&
981 [ + + ]: 340 : lVis->blkno != InvalidBlockNumber &&
982 [ - + ]: 9 : lVis->blkno != targetblock)
983 : : {
780 akorotkov@postgresql 984 :UBC 0 : char *posting = "";
985 : :
572 986 [ # # ]: 0 : if (lVis->postingIndex >= 0)
987 : 0 : posting = psprintf(" posting %u", lVis->postingIndex);
780 988 [ # # ]: 0 : ereport(DEBUG1,
989 : : (errcode(ERRCODE_NO_DATA),
990 : : errmsg("index uniqueness can not be checked for index tid=(%u,%u) in index \"%s\"",
991 : : targetblock, offset,
992 : : RelationGetRelationName(state->rel)),
993 : : errdetail("It doesn't have visible heap tids and key is equal to the tid=(%u,%u)%s (points to heap tid=(%u,%u)).",
994 : : lVis->blkno, lVis->offset, posting,
995 : : ItemPointerGetBlockNumberNoCheck(lVis->tid),
996 : : ItemPointerGetOffsetNumberNoCheck(lVis->tid)),
997 : : errhint("VACUUM the table and repeat the check.")));
998 : : }
999 : : }
1000 : :
1001 : : /*
1002 : : * Like P_LEFTMOST(start_opaque), but accept an arbitrarily-long chain of
1003 : : * half-dead, sibling-linked pages to the left. If a half-dead page appears
1004 : : * under state->readonly, the database exited recovery between the first-stage
1005 : : * and second-stage WAL records of a deletion.
1006 : : */
1007 : : static bool
778 noah@leadboat.com 1008 :CBC 56 : bt_leftmost_ignoring_half_dead(BtreeCheckState *state,
1009 : : BlockNumber start,
1010 : : BTPageOpaque start_opaque)
1011 : : {
1012 : 56 : BlockNumber reached = start_opaque->btpo_prev,
1013 : 56 : reached_from = start;
1014 : 56 : bool all_half_dead = true;
1015 : :
1016 : : /*
1017 : : * To handle the !readonly case, we'd need to accept BTP_DELETED pages and
1018 : : * potentially observe nbtree/README "Page deletion and backwards scans".
1019 : : */
1020 [ - + ]: 56 : Assert(state->readonly);
1021 : :
1022 [ + + + - ]: 58 : while (reached != P_NONE && all_half_dead)
1023 : : {
1024 : 2 : Page page = palloc_btree_page(state, reached);
1025 : 2 : BTPageOpaque reached_opaque = BTPageGetOpaque(page);
1026 : :
1027 [ - + ]: 2 : CHECK_FOR_INTERRUPTS();
1028 : :
1029 : : /*
1030 : : * Try to detect btpo_prev circular links. _bt_unlink_halfdead_page()
1031 : : * writes that side-links will continue to point to the siblings.
1032 : : * Check btpo_next for that property.
1033 : : */
1034 [ + - ]: 2 : all_half_dead = P_ISHALFDEAD(reached_opaque) &&
1035 [ + - ]: 2 : reached != start &&
1036 [ + - ]: 4 : reached != reached_from &&
1037 [ + - ]: 2 : reached_opaque->btpo_next == reached_from;
1038 [ + - ]: 2 : if (all_half_dead)
1039 : : {
1040 : 2 : XLogRecPtr pagelsn = PageGetLSN(page);
1041 : :
1042 : : /* pagelsn should point to an XLOG_BTREE_MARK_PAGE_HALFDEAD */
1043 [ + - ]: 2 : ereport(DEBUG1,
1044 : : (errcode(ERRCODE_NO_DATA),
1045 : : errmsg_internal("harmless interrupted page deletion detected in index \"%s\"",
1046 : : RelationGetRelationName(state->rel)),
1047 : : errdetail_internal("Block=%u right block=%u page lsn=%X/%08X.",
1048 : : reached, reached_from,
1049 : : LSN_FORMAT_ARGS(pagelsn))));
1050 : :
1051 : 2 : reached_from = reached;
1052 : 2 : reached = reached_opaque->btpo_prev;
1053 : : }
1054 : :
1055 : 2 : pfree(page);
1056 : : }
1057 : :
1058 : 56 : return all_half_dead;
1059 : : }
1060 : :
1061 : : /*
1062 : : * Raise an error when target page's left link does not point back to the
1063 : : * previous target page, called leftcurrent here. The leftcurrent page's
1064 : : * right link was followed to get to the current target page, and we expect
1065 : : * mutual agreement among leftcurrent and the current target page. Make sure
1066 : : * that this condition has definitely been violated in the !readonly case,
1067 : : * where concurrent page splits are something that we need to deal with.
1068 : : *
1069 : : * Cross-page inconsistencies involving pages that don't agree about being
1070 : : * siblings are known to be a particularly good indicator of corruption
1071 : : * involving partial writes/lost updates. The bt_right_page_check_scankey
1072 : : * check also provides a way of detecting cross-page inconsistencies for
1073 : : * !readonly callers, but it can only detect sibling pages that have an
1074 : : * out-of-order keyspace, which can't catch many of the problems that we
1075 : : * expect to catch here.
1076 : : *
1077 : : * The classic example of the kind of inconsistency that we can only catch
1078 : : * with this check (when in !readonly mode) involves three sibling pages that
1079 : : * were affected by a faulty page split at some point in the past. The
1080 : : * effects of the split are reflected in the original page and its new right
1081 : : * sibling page, with a lack of any accompanying changes for the _original_
1082 : : * right sibling page. The original right sibling page's left link fails to
1083 : : * point to the new right sibling page (its left link still points to the
1084 : : * original page), even though the first phase of a page split is supposed to
1085 : : * work as a single atomic action. This subtle inconsistency will probably
1086 : : * only break backwards scans in practice.
1087 : : *
1088 : : * Note that this is the only place where amcheck will "couple" buffer locks
1089 : : * (and only for !readonly callers). In general we prefer to avoid more
1090 : : * thorough cross-page checks in !readonly mode, but it seems worth the
1091 : : * complexity here. Also, the performance overhead of performing lock
1092 : : * coupling here is negligible in practice. Control only reaches here with a
1093 : : * non-corrupt index when there is a concurrent page split at the instant
1094 : : * caller crossed over to target page from leftcurrent page.
1095 : : */
1096 : : static void
1956 pg@bowt.ie 1097 :UBC 0 : bt_recheck_sibling_links(BtreeCheckState *state,
1098 : : BlockNumber btpo_prev_from_target,
1099 : : BlockNumber leftcurrent)
1100 : : {
1101 : : /* passing metapage to BTPageGetOpaque() would give irrelevant findings */
778 noah@leadboat.com 1102 [ # # ]: 0 : Assert(leftcurrent != P_NONE);
1103 : :
1956 pg@bowt.ie 1104 [ # # ]: 0 : if (!state->readonly)
1105 : : {
1106 : : Buffer lbuf;
1107 : : Buffer newtargetbuf;
1108 : : Page page;
1109 : : BTPageOpaque opaque;
1110 : : BlockNumber newtargetblock;
1111 : :
1112 : : /* Couple locks in the usual order for nbtree: Left to right */
1113 : 0 : lbuf = ReadBufferExtended(state->rel, MAIN_FORKNUM, leftcurrent,
1114 : : RBM_NORMAL, state->checkstrategy);
1115 : 0 : LockBuffer(lbuf, BT_READ);
1116 : 0 : _bt_checkpage(state->rel, lbuf);
1117 : 0 : page = BufferGetPage(lbuf);
1355 michael@paquier.xyz 1118 : 0 : opaque = BTPageGetOpaque(page);
1956 pg@bowt.ie 1119 [ # # ]: 0 : if (P_ISDELETED(opaque))
1120 : : {
1121 : : /*
1122 : : * Cannot reason about concurrently deleted page -- the left link
1123 : : * in the page to the right is expected to point to some other
1124 : : * page to the left (not leftcurrent page).
1125 : : *
1126 : : * Note that we deliberately don't give up with a half-dead page.
1127 : : */
1128 : 0 : UnlockReleaseBuffer(lbuf);
1129 : 0 : return;
1130 : : }
1131 : :
1132 : 0 : newtargetblock = opaque->btpo_next;
1133 : : /* Avoid self-deadlock when newtargetblock == leftcurrent */
1134 [ # # ]: 0 : if (newtargetblock != leftcurrent)
1135 : : {
1136 : 0 : newtargetbuf = ReadBufferExtended(state->rel, MAIN_FORKNUM,
1137 : : newtargetblock, RBM_NORMAL,
1138 : : state->checkstrategy);
1139 : 0 : LockBuffer(newtargetbuf, BT_READ);
1140 : 0 : _bt_checkpage(state->rel, newtargetbuf);
1141 : 0 : page = BufferGetPage(newtargetbuf);
1355 michael@paquier.xyz 1142 : 0 : opaque = BTPageGetOpaque(page);
1143 : : /* btpo_prev_from_target may have changed; update it */
1956 pg@bowt.ie 1144 : 0 : btpo_prev_from_target = opaque->btpo_prev;
1145 : : }
1146 : : else
1147 : : {
1148 : : /*
1149 : : * leftcurrent right sibling points back to leftcurrent block.
1150 : : * Index is corrupt. Easiest way to handle this is to pretend
1151 : : * that we actually read from a distinct page that has an invalid
1152 : : * block number in its btpo_prev.
1153 : : */
1154 : 0 : newtargetbuf = InvalidBuffer;
1155 : 0 : btpo_prev_from_target = InvalidBlockNumber;
1156 : : }
1157 : :
1158 : : /*
1159 : : * No need to check P_ISDELETED here, since new target block cannot be
1160 : : * marked deleted as long as we hold a lock on lbuf
1161 : : */
1162 [ # # ]: 0 : if (BufferIsValid(newtargetbuf))
1163 : 0 : UnlockReleaseBuffer(newtargetbuf);
1164 : 0 : UnlockReleaseBuffer(lbuf);
1165 : :
1166 [ # # ]: 0 : if (btpo_prev_from_target == leftcurrent)
1167 : : {
1168 : : /* Report split in left sibling, not target (or new target) */
1169 [ # # ]: 0 : ereport(DEBUG1,
1170 : : (errcode(ERRCODE_INTERNAL_ERROR),
1171 : : errmsg_internal("harmless concurrent page split detected in index \"%s\"",
1172 : : RelationGetRelationName(state->rel)),
1173 : : errdetail_internal("Block=%u new right sibling=%u original right sibling=%u.",
1174 : : leftcurrent, newtargetblock,
1175 : : state->targetblock)));
1176 : 0 : return;
1177 : : }
1178 : :
1179 : : /*
1180 : : * Index is corrupt. Make sure that we report correct target page.
1181 : : *
1182 : : * This could have changed in cases where there was a concurrent page
1183 : : * split, as well as index corruption (at least in theory). Note that
1184 : : * btpo_prev_from_target was already updated above.
1185 : : */
1186 : 0 : state->targetblock = newtargetblock;
1187 : : }
1188 : :
1189 [ # # ]: 0 : ereport(ERROR,
1190 : : (errcode(ERRCODE_INDEX_CORRUPTED),
1191 : : errmsg("left link/right link pair in index \"%s\" not in agreement",
1192 : : RelationGetRelationName(state->rel)),
1193 : : errdetail_internal("Block=%u left block=%u left link from block=%u.",
1194 : : state->targetblock, leftcurrent,
1195 : : btpo_prev_from_target)));
1196 : : }
1197 : :
1198 : : /*
1199 : : * Function performs the following checks on target page, or pages ancillary to
1200 : : * target page:
1201 : : *
1202 : : * - That every "real" data item is less than or equal to the high key, which
1203 : : * is an upper bound on the items on the page. Data items should be
1204 : : * strictly less than the high key when the page is an internal page.
1205 : : *
1206 : : * - That within the page, every data item is strictly less than the item
1207 : : * immediately to its right, if any (i.e., that the items are in order
1208 : : * within the page, so that the binary searches performed by index scans are
1209 : : * sane).
1210 : : *
1211 : : * - That the last data item stored on the page is strictly less than the
1212 : : * first data item on the page to the right (when such a first item is
1213 : : * available).
1214 : : *
1215 : : * - Various checks on the structure of tuples themselves. For example, check
1216 : : * that non-pivot tuples have no truncated attributes.
1217 : : *
1218 : : * - For index with unique constraint make sure that only one of table entries
1219 : : * for equal keys is visible.
1220 : : *
1221 : : * Furthermore, when state passed shows ShareLock held, function also checks:
1222 : : *
1223 : : * - That all child pages respect strict lower bound from parent's pivot
1224 : : * tuple.
1225 : : *
1226 : : * - That downlink to block was encountered in parent where that's expected.
1227 : : *
1228 : : * - That high keys of child pages matches corresponding pivot keys in parent.
1229 : : *
1230 : : * This is also where heapallindexed callers use their Bloom filter to
1231 : : * fingerprint IndexTuples for later table_index_build_scan() verification.
1232 : : *
1233 : : * Note: Memory allocated in this routine is expected to be released by caller
1234 : : * resetting state->targetcontext.
1235 : : */
1236 : : static void
3204 andres@anarazel.de 1237 :CBC 9304 : bt_target_page_check(BtreeCheckState *state)
1238 : : {
1239 : : OffsetNumber offset;
1240 : : OffsetNumber max;
1241 : : BTPageOpaque topaque;
1242 : :
1243 : : /* Last visible entry info for checking indexes with unique constraint */
572 akorotkov@postgresql 1244 : 9304 : BtreeLastVisibleEntry lVis = {InvalidBlockNumber, InvalidOffsetNumber, -1, NULL};
1245 : :
1355 michael@paquier.xyz 1246 : 9304 : topaque = BTPageGetOpaque(state->target);
3204 andres@anarazel.de 1247 : 9304 : max = PageGetMaxOffsetNumber(state->target);
1248 : :
1249 [ - + - - ]: 9304 : elog(DEBUG2, "verifying %u items on %s block %u", max,
1250 : : P_ISLEAF(topaque) ? "leaf" : "internal", state->targetblock);
1251 : :
1252 : : /*
1253 : : * Check the number of attributes in high key. Note, rightmost page
1254 : : * doesn't contain a high key, so nothing to check
1255 : : */
2427 pg@bowt.ie 1256 [ + + ]: 9304 : if (!P_RIGHTMOST(topaque))
1257 : : {
1258 : : ItemId itemid;
1259 : : IndexTuple itup;
1260 : :
1261 : : /* Verify line pointer before checking tuple */
1262 : 6807 : itemid = PageGetItemIdCareful(state, state->targetblock,
1263 : : state->target, P_HIKEY);
1264 [ - + ]: 6807 : if (!_bt_check_natts(state->rel, state->heapkeyspace, state->target,
1265 : : P_HIKEY))
1266 : : {
2427 pg@bowt.ie 1267 :UBC 0 : itup = (IndexTuple) PageGetItem(state->target, itemid);
1268 [ # # # # : 0 : ereport(ERROR,
# # ]
1269 : : (errcode(ERRCODE_INDEX_CORRUPTED),
1270 : : errmsg("wrong number of high key index tuple attributes in index \"%s\"",
1271 : : RelationGetRelationName(state->rel)),
1272 : : errdetail_internal("Index block=%u natts=%u block type=%s page lsn=%X/%08X.",
1273 : : state->targetblock,
1274 : : BTreeTupleGetNAtts(itup, state->rel),
1275 : : P_ISLEAF(topaque) ? "heap" : "index",
1276 : : LSN_FORMAT_ARGS(state->targetlsn))));
1277 : : }
1278 : : }
1279 : :
1280 : : /*
1281 : : * Loop over page items, starting from first non-highkey item, not high
1282 : : * key (if any). Most tests are not performed for the "negative infinity"
1283 : : * real item (if any).
1284 : : */
3204 andres@anarazel.de 1285 [ + + ]:CBC 9304 : for (offset = P_FIRSTDATAKEY(topaque);
1286 [ + + ]: 2064455 : offset <= max;
1287 : 2055151 : offset = OffsetNumberNext(offset))
1288 : : {
1289 : : ItemId itemid;
1290 : : IndexTuple itup;
1291 : : size_t tupsize;
1292 : : BTScanInsert skey;
1293 : : bool lowersizelimit;
1294 : : ItemPointer scantid;
1295 : :
1296 : : /*
1297 : : * True if we already called bt_entry_unique_check() for the current
1298 : : * item. This helps to avoid visiting the heap for keys, which are
1299 : : * anyway presented only once and can't comprise a unique violation.
1300 : : */
506 akorotkov@postgresql 1301 : 2055157 : bool unique_checked = false;
1302 : :
3204 andres@anarazel.de 1303 [ - + ]: 2055157 : CHECK_FOR_INTERRUPTS();
1304 : :
2427 pg@bowt.ie 1305 : 2055157 : itemid = PageGetItemIdCareful(state, state->targetblock,
1306 : : state->target, offset);
2817 andres@anarazel.de 1307 : 2055157 : itup = (IndexTuple) PageGetItem(state->target, itemid);
1308 : 2055157 : tupsize = IndexTupleSize(itup);
1309 : :
1310 : : /*
1311 : : * lp_len should match the IndexTuple reported length exactly, since
1312 : : * lp_len is completely redundant in indexes, and both sources of
1313 : : * tuple length are MAXALIGN()'d. nbtree does not use lp_len all that
1314 : : * frequently, and is surprisingly tolerant of corrupt lp_len fields.
1315 : : */
1316 [ - + ]: 2055157 : if (tupsize != ItemIdGetLength(itemid))
2817 andres@anarazel.de 1317 [ # # ]:UBC 0 : ereport(ERROR,
1318 : : (errcode(ERRCODE_INDEX_CORRUPTED),
1319 : : errmsg("index tuple size does not equal lp_len in index \"%s\"",
1320 : : RelationGetRelationName(state->rel)),
1321 : : errdetail_internal("Index tid=(%u,%u) tuple size=%zu lp_len=%u page lsn=%X/%08X.",
1322 : : state->targetblock, offset,
1323 : : tupsize, ItemIdGetLength(itemid),
1324 : : LSN_FORMAT_ARGS(state->targetlsn)),
1325 : : errhint("This could be a torn page problem.")));
1326 : :
1327 : : /* Check the number of index tuple attributes */
2463 pg@bowt.ie 1328 [ - + ]:CBC 2055157 : if (!_bt_check_natts(state->rel, state->heapkeyspace, state->target,
1329 : : offset))
1330 : : {
1331 : : ItemPointer tid;
1332 : : char *itid,
1333 : : *htid;
1334 : :
2810 teodor@sigaev.ru 1335 :UBC 0 : itid = psprintf("(%u,%u)", state->targetblock, offset);
2120 pg@bowt.ie 1336 : 0 : tid = BTreeTupleGetPointsToTID(itup);
2810 teodor@sigaev.ru 1337 : 0 : htid = psprintf("(%u,%u)",
1338 : : ItemPointerGetBlockNumberNoCheck(tid),
2120 pg@bowt.ie 1339 : 0 : ItemPointerGetOffsetNumberNoCheck(tid));
1340 : :
2810 teodor@sigaev.ru 1341 [ # # # # : 0 : ereport(ERROR,
# # ]
1342 : : (errcode(ERRCODE_INDEX_CORRUPTED),
1343 : : errmsg("wrong number of index tuple attributes in index \"%s\"",
1344 : : RelationGetRelationName(state->rel)),
1345 : : errdetail_internal("Index tid=%s natts=%u points to %s tid=%s page lsn=%X/%08X.",
1346 : : itid,
1347 : : BTreeTupleGetNAtts(itup, state->rel),
1348 : : P_ISLEAF(topaque) ? "heap" : "index",
1349 : : htid,
1350 : : LSN_FORMAT_ARGS(state->targetlsn))));
1351 : : }
1352 : :
1353 : : /*
1354 : : * Don't try to generate scankey using "negative infinity" item on
1355 : : * internal pages. They are always truncated to zero attributes.
1356 : : */
3204 andres@anarazel.de 1357 [ + + ]:CBC 2055157 : if (offset_is_negative_infinity(topaque, offset))
1358 : : {
1359 : : /*
1360 : : * We don't call bt_child_check() for "negative infinity" items.
1361 : : * But if we're performing downlink connectivity check, we do it
1362 : : * for every item including "negative infinity" one.
1363 : : */
2106 akorotkov@postgresql 1364 [ + - + + ]: 557 : if (!P_ISLEAF(topaque) && state->readonly)
1365 : : {
1366 : 12 : bt_child_highkey_check(state,
1367 : : offset,
1368 : : NULL,
1369 : : topaque->btpo_level);
1370 : : }
3204 andres@anarazel.de 1371 : 557 : continue;
1372 : : }
1373 : :
1374 : : /*
1375 : : * Readonly callers may optionally verify that non-pivot tuples can
1376 : : * each be found by an independent search that starts from the root.
1377 : : * Note that we deliberately don't do individual searches for each
1378 : : * TID, since the posting list itself is validated by other checks.
1379 : : */
2463 pg@bowt.ie 1380 [ + + + + ]: 2054600 : if (state->rootdescend && P_ISLEAF(topaque) &&
1381 [ - + ]: 201098 : !bt_rootdescend(state, itup))
1382 : : {
2120 pg@bowt.ie 1383 :UBC 0 : ItemPointer tid = BTreeTupleGetPointsToTID(itup);
1384 : : char *itid,
1385 : : *htid;
1386 : :
2463 1387 : 0 : itid = psprintf("(%u,%u)", state->targetblock, offset);
2120 1388 : 0 : htid = psprintf("(%u,%u)", ItemPointerGetBlockNumber(tid),
1389 : 0 : ItemPointerGetOffsetNumber(tid));
1390 : :
2463 1391 [ # # ]: 0 : ereport(ERROR,
1392 : : (errcode(ERRCODE_INDEX_CORRUPTED),
1393 : : errmsg("could not find tuple using search from root page in index \"%s\"",
1394 : : RelationGetRelationName(state->rel)),
1395 : : errdetail_internal("Index tid=%s points to heap tid=%s page lsn=%X/%08X.",
1396 : : itid, htid,
1397 : : LSN_FORMAT_ARGS(state->targetlsn))));
1398 : : }
1399 : :
1400 : : /*
1401 : : * If tuple is a posting list tuple, make sure posting list TIDs are
1402 : : * in order
1403 : : */
2120 pg@bowt.ie 1404 [ + + ]:CBC 2054600 : if (BTreeTupleIsPosting(itup))
1405 : : {
1406 : : ItemPointerData last;
1407 : : ItemPointer current;
1408 : :
1409 : 11159 : ItemPointerCopy(BTreeTupleGetHeapTID(itup), &last);
1410 : :
1411 [ + + ]: 80881 : for (int i = 1; i < BTreeTupleGetNPosting(itup); i++)
1412 : : {
1413 : :
1414 : 69722 : current = BTreeTupleGetPostingN(itup, i);
1415 : :
1416 [ - + ]: 69722 : if (ItemPointerCompare(current, &last) <= 0)
1417 : : {
2120 pg@bowt.ie 1418 :UBC 0 : char *itid = psprintf("(%u,%u)", state->targetblock, offset);
1419 : :
1420 [ # # ]: 0 : ereport(ERROR,
1421 : : (errcode(ERRCODE_INDEX_CORRUPTED),
1422 : : errmsg_internal("posting list contains misplaced TID in index \"%s\"",
1423 : : RelationGetRelationName(state->rel)),
1424 : : errdetail_internal("Index tid=%s posting list offset=%d page lsn=%X/%08X.",
1425 : : itid, i,
1426 : : LSN_FORMAT_ARGS(state->targetlsn))));
1427 : : }
1428 : :
2120 pg@bowt.ie 1429 :CBC 69722 : ItemPointerCopy(current, &last);
1430 : : }
1431 : : }
1432 : :
1433 : : /* Build insertion scankey for current page offset */
920 1434 : 2054600 : skey = bt_mkscankey_pivotsearch(state->rel, itup);
1435 : :
1436 : : /*
1437 : : * Make sure tuple size does not exceed the relevant BTREE_VERSION
1438 : : * specific limit.
1439 : : *
1440 : : * BTREE_VERSION 4 (which introduced heapkeyspace rules) requisitioned
1441 : : * a small amount of space from BTMaxItemSize() in order to ensure
1442 : : * that suffix truncation always has enough space to add an explicit
1443 : : * heap TID back to a tuple -- we pessimistically assume that every
1444 : : * newly inserted tuple will eventually need to have a heap TID
1445 : : * appended during a future leaf page split, when the tuple becomes
1446 : : * the basis of the new high key (pivot tuple) for the leaf page.
1447 : : *
1448 : : * Since the reclaimed space is reserved for that purpose, we must not
1449 : : * enforce the slightly lower limit when the extra space has been used
1450 : : * as intended. In other words, there is only a cross-version
1451 : : * difference in the limit on tuple size within leaf pages.
1452 : : *
1453 : : * Still, we're particular about the details within BTREE_VERSION 4
1454 : : * internal pages. Pivot tuples may only use the extra space for its
1455 : : * designated purpose. Enforce the lower limit for pivot tuples when
1456 : : * an explicit heap TID isn't actually present. (In all other cases
1457 : : * suffix truncation is guaranteed to generate a pivot tuple that's no
1458 : : * larger than the firstright tuple provided to it by its caller.)
1459 : : */
2463 1460 [ + - ]: 4109200 : lowersizelimit = skey->heapkeyspace &&
1461 [ + + + + ]: 2054600 : (P_ISLEAF(topaque) || BTreeTupleGetHeapTID(itup) == NULL);
280 1462 [ + + - + ]: 2054600 : if (tupsize > (lowersizelimit ? BTMaxItemSize : BTMaxItemSizeNoHeapTid))
1463 : : {
2120 pg@bowt.ie 1464 :UBC 0 : ItemPointer tid = BTreeTupleGetPointsToTID(itup);
1465 : : char *itid,
1466 : : *htid;
1467 : :
2463 1468 : 0 : itid = psprintf("(%u,%u)", state->targetblock, offset);
1469 : 0 : htid = psprintf("(%u,%u)",
1470 : : ItemPointerGetBlockNumberNoCheck(tid),
2120 1471 : 0 : ItemPointerGetOffsetNumberNoCheck(tid));
1472 : :
2463 1473 [ # # # # ]: 0 : ereport(ERROR,
1474 : : (errcode(ERRCODE_INDEX_CORRUPTED),
1475 : : errmsg("index row size %zu exceeds maximum for index \"%s\"",
1476 : : tupsize, RelationGetRelationName(state->rel)),
1477 : : errdetail_internal("Index tid=%s points to %s tid=%s page lsn=%X/%08X.",
1478 : : itid,
1479 : : P_ISLEAF(topaque) ? "heap" : "index",
1480 : : htid,
1481 : : LSN_FORMAT_ARGS(state->targetlsn))));
1482 : : }
1483 : :
1484 : : /* Fingerprint leaf page tuples (those that point to the heap) */
2817 andres@anarazel.de 1485 [ + + + + :CBC 2054600 : if (state->heapallindexed && P_ISLEAF(topaque) && !ItemIdIsDead(itemid))
+ - ]
1486 : : {
1487 : : IndexTuple norm;
1488 : :
2120 pg@bowt.ie 1489 [ + + ]: 507015 : if (BTreeTupleIsPosting(itup))
1490 : : {
1491 : : /* Fingerprint all elements as distinct "plain" tuples */
1492 [ + + ]: 27648 : for (int i = 0; i < BTreeTupleGetNPosting(itup); i++)
1493 : : {
1494 : : IndexTuple logtuple;
1495 : :
1496 : 27449 : logtuple = bt_posting_plain_tuple(itup, i);
1497 : 27449 : norm = bt_normalize_tuple(state, logtuple);
1498 : 27449 : bloom_add_element(state->filter, (unsigned char *) norm,
1499 : : IndexTupleSize(norm));
1500 : : /* Be tidy */
1501 [ + + ]: 27449 : if (norm != logtuple)
1502 : 2 : pfree(norm);
1503 : 27449 : pfree(logtuple);
1504 : : }
1505 : : }
1506 : : else
1507 : : {
1508 : 506816 : norm = bt_normalize_tuple(state, itup);
1509 : 506816 : bloom_add_element(state->filter, (unsigned char *) norm,
1510 : : IndexTupleSize(norm));
1511 : : /* Be tidy */
1512 [ + + ]: 506816 : if (norm != itup)
1513 : 1 : pfree(norm);
1514 : : }
1515 : : }
1516 : :
1517 : : /*
1518 : : * * High key check *
1519 : : *
1520 : : * If there is a high key (if this is not the rightmost page on its
1521 : : * entire level), check that high key actually is upper bound on all
1522 : : * page items. If this is a posting list tuple, we'll need to set
1523 : : * scantid to be highest TID in posting list.
1524 : : *
1525 : : * We prefer to check all items against high key rather than checking
1526 : : * just the last and trusting that the operator class obeys the
1527 : : * transitive law (which implies that all previous items also
1528 : : * respected the high key invariant if they pass the item order
1529 : : * check).
1530 : : *
1531 : : * Ideally, we'd compare every item in the index against every other
1532 : : * item in the index, and not trust opclass obedience of the
1533 : : * transitive law to bridge the gap between children and their
1534 : : * grandparents (as well as great-grandparents, and so on). We don't
1535 : : * go to those lengths because that would be prohibitively expensive,
1536 : : * and probably not markedly more effective in practice.
1537 : : *
1538 : : * On the leaf level, we check that the key is <= the highkey.
1539 : : * However, on non-leaf levels we check that the key is < the highkey,
1540 : : * because the high key is "just another separator" rather than a copy
1541 : : * of some existing key item; we expect it to be unique among all keys
1542 : : * on the same level. (Suffix truncation will sometimes produce a
1543 : : * leaf highkey that is an untruncated copy of the lastleft item, but
1544 : : * never any other item, which necessitates weakening the leaf level
1545 : : * check to <=.)
1546 : : *
1547 : : * Full explanation for why a highkey is never truly a copy of another
1548 : : * item from the same level on internal levels:
1549 : : *
1550 : : * While the new left page's high key is copied from the first offset
1551 : : * on the right page during an internal page split, that's not the
1552 : : * full story. In effect, internal pages are split in the middle of
1553 : : * the firstright tuple, not between the would-be lastleft and
1554 : : * firstright tuples: the firstright key ends up on the left side as
1555 : : * left's new highkey, and the firstright downlink ends up on the
1556 : : * right side as right's new "negative infinity" item. The negative
1557 : : * infinity tuple is truncated to zero attributes, so we're only left
1558 : : * with the downlink. In other words, the copying is just an
1559 : : * implementation detail of splitting in the middle of a (pivot)
1560 : : * tuple. (See also: "Notes About Data Representation" in the nbtree
1561 : : * README.)
1562 : : */
1563 : 2054600 : scantid = skey->scantid;
1564 [ + - + + ]: 2054600 : if (state->heapkeyspace && BTreeTupleIsPosting(itup))
1565 : 11159 : skey->scantid = BTreeTupleGetMaxHeapTID(itup);
1566 : :
3204 andres@anarazel.de 1567 [ + + - + ]: 3937681 : if (!P_RIGHTMOST(topaque) &&
2463 pg@bowt.ie 1568 [ + + ]: 1883081 : !(P_ISLEAF(topaque) ? invariant_leq_offset(state, skey, P_HIKEY) :
1569 : 566 : invariant_l_offset(state, skey, P_HIKEY)))
1570 : : {
2120 pg@bowt.ie 1571 :UBC 0 : ItemPointer tid = BTreeTupleGetPointsToTID(itup);
1572 : : char *itid,
1573 : : *htid;
1574 : :
3204 andres@anarazel.de 1575 : 0 : itid = psprintf("(%u,%u)", state->targetblock, offset);
1576 : 0 : htid = psprintf("(%u,%u)",
1577 : : ItemPointerGetBlockNumberNoCheck(tid),
2120 pg@bowt.ie 1578 : 0 : ItemPointerGetOffsetNumberNoCheck(tid));
1579 : :
3204 andres@anarazel.de 1580 [ # # # # ]: 0 : ereport(ERROR,
1581 : : (errcode(ERRCODE_INDEX_CORRUPTED),
1582 : : errmsg("high key invariant violated for index \"%s\"",
1583 : : RelationGetRelationName(state->rel)),
1584 : : errdetail_internal("Index tid=%s points to %s tid=%s page lsn=%X/%08X.",
1585 : : itid,
1586 : : P_ISLEAF(topaque) ? "heap" : "index",
1587 : : htid,
1588 : : LSN_FORMAT_ARGS(state->targetlsn))));
1589 : : }
1590 : : /* Reset, in case scantid was set to (itup) posting tuple's max TID */
2120 pg@bowt.ie 1591 :CBC 2054600 : skey->scantid = scantid;
1592 : :
1593 : : /*
1594 : : * * Item order check *
1595 : : *
1596 : : * Check that items are stored on page in logical order, by checking
1597 : : * current item is strictly less than next item (if any).
1598 : : */
3204 andres@anarazel.de 1599 [ + + ]: 2054600 : if (OffsetNumberNext(offset) <= max &&
2463 pg@bowt.ie 1600 [ + + ]: 2045304 : !invariant_l_offset(state, skey, OffsetNumberNext(offset)))
1601 : : {
1602 : : ItemPointer tid;
1603 : : char *itid,
1604 : : *htid,
1605 : : *nitid,
1606 : : *nhtid;
1607 : :
3204 andres@anarazel.de 1608 : 3 : itid = psprintf("(%u,%u)", state->targetblock, offset);
2120 pg@bowt.ie 1609 : 3 : tid = BTreeTupleGetPointsToTID(itup);
3204 andres@anarazel.de 1610 : 3 : htid = psprintf("(%u,%u)",
1611 : : ItemPointerGetBlockNumberNoCheck(tid),
2120 pg@bowt.ie 1612 : 3 : ItemPointerGetOffsetNumberNoCheck(tid));
3204 andres@anarazel.de 1613 : 3 : nitid = psprintf("(%u,%u)", state->targetblock,
1614 : 3 : OffsetNumberNext(offset));
1615 : :
1616 : : /* Reuse itup to get pointed-to heap location of second item */
2427 pg@bowt.ie 1617 : 3 : itemid = PageGetItemIdCareful(state, state->targetblock,
1618 : : state->target,
1619 : 3 : OffsetNumberNext(offset));
3204 andres@anarazel.de 1620 : 3 : itup = (IndexTuple) PageGetItem(state->target, itemid);
2120 pg@bowt.ie 1621 : 3 : tid = BTreeTupleGetPointsToTID(itup);
3204 andres@anarazel.de 1622 : 3 : nhtid = psprintf("(%u,%u)",
1623 : : ItemPointerGetBlockNumberNoCheck(tid),
2120 pg@bowt.ie 1624 : 3 : ItemPointerGetOffsetNumberNoCheck(tid));
1625 : :
3204 andres@anarazel.de 1626 [ + - + + : 3 : ereport(ERROR,
+ + ]
1627 : : (errcode(ERRCODE_INDEX_CORRUPTED),
1628 : : errmsg("item order invariant violated for index \"%s\"",
1629 : : RelationGetRelationName(state->rel)),
1630 : : errdetail_internal("Lower index tid=%s (points to %s tid=%s) higher index tid=%s (points to %s tid=%s) page lsn=%X/%08X.",
1631 : : itid,
1632 : : P_ISLEAF(topaque) ? "heap" : "index",
1633 : : htid,
1634 : : nitid,
1635 : : P_ISLEAF(topaque) ? "heap" : "index",
1636 : : nhtid,
1637 : : LSN_FORMAT_ARGS(state->targetlsn))));
1638 : : }
1639 : :
1640 : : /*
1641 : : * If the index is unique verify entries uniqueness by checking the
1642 : : * heap tuples visibility. Immediately check posting tuples and
1643 : : * tuples with repeated keys. Postpone check for keys, which have the
1644 : : * first appearance.
1645 : : */
780 akorotkov@postgresql 1646 [ + + + + ]: 2054597 : if (state->checkunique && state->indexinfo->ii_Unique &&
506 1647 [ + + + + : 301355 : P_ISLEAF(topaque) && !skey->anynullkeys &&
+ + ]
1648 [ + + ]: 300708 : (BTreeTupleIsPosting(itup) || ItemPointerIsValid(lVis.tid)))
1649 : : {
780 1650 : 28 : bt_entry_unique_check(state, itup, state->targetblock, offset,
1651 : : &lVis);
506 1652 : 25 : unique_checked = true;
1653 : : }
1654 : :
780 1655 [ + + + + ]: 2054594 : if (state->checkunique && state->indexinfo->ii_Unique &&
1656 [ + + + + ]: 150990 : P_ISLEAF(topaque) && OffsetNumberNext(offset) <= max)
1657 : : {
1658 : : /* Save current scankey tid */
1659 : 149602 : scantid = skey->scantid;
1660 : :
1661 : : /*
1662 : : * Invalidate scankey tid to make _bt_compare compare only keys in
1663 : : * the item to report equality even if heap TIDs are different
1664 : : */
1665 : 149602 : skey->scantid = NULL;
1666 : :
1667 : : /*
1668 : : * If next key tuple is different, invalidate last visible entry
1669 : : * data (whole index tuple or last posting in index tuple). Key
1670 : : * containing null value does not violate unique constraint and
1671 : : * treated as different to any other key.
1672 : : *
1673 : : * If the next key is the same as the previous one, do the
1674 : : * bt_entry_unique_check() call if it was postponed.
1675 : : */
1676 [ + + ]: 149602 : if (_bt_compare(state->rel, skey, state->target,
1677 [ + + ]: 150015 : OffsetNumberNext(offset)) != 0 || skey->anynullkeys)
1678 : : {
572 1679 : 149259 : lVis.blkno = InvalidBlockNumber;
1680 : 149259 : lVis.offset = InvalidOffsetNumber;
1681 : 149259 : lVis.postingIndex = -1;
1682 : 149259 : lVis.tid = NULL;
1683 : : }
506 1684 [ + - ]: 343 : else if (!unique_checked)
1685 : : {
1686 : 343 : bt_entry_unique_check(state, itup, state->targetblock, offset,
1687 : : &lVis);
1688 : : }
780 1689 : 149602 : skey->scantid = scantid; /* Restore saved scan key state */
1690 : : }
1691 : :
1692 : : /*
1693 : : * * Last item check *
1694 : : *
1695 : : * Check last item against next/right page's first data item's when
1696 : : * last item on page is reached. This additional check will detect
1697 : : * transposed pages iff the supposed right sibling page happens to
1698 : : * belong before target in the key space. (Otherwise, a subsequent
1699 : : * heap verification will probably detect the problem.)
1700 : : *
1701 : : * This check is similar to the item order check that will have
1702 : : * already been performed for every other "real" item on target page
1703 : : * when last item is checked. The difference is that the next item
1704 : : * (the item that is compared to target's last item) needs to come
1705 : : * from the next/sibling page. There may not be such an item
1706 : : * available from sibling for various reasons, though (e.g., target is
1707 : : * the rightmost page on level).
1708 : : */
1709 [ + + ]: 2054594 : if (offset == max)
1710 : : {
1711 : : BTScanInsert rightkey;
1712 : :
1713 : : /* first offset on a right index page (log only) */
1714 : 9296 : OffsetNumber rightfirstoffset = InvalidOffsetNumber;
1715 : :
1716 : : /* Get item in next/right page */
1717 : 9296 : rightkey = bt_right_page_check_scankey(state, &rightfirstoffset);
1718 : :
3204 andres@anarazel.de 1719 [ + + ]: 9296 : if (rightkey &&
2463 pg@bowt.ie 1720 [ - + ]: 6803 : !invariant_g_offset(state, rightkey, max))
1721 : : {
1722 : : /*
1723 : : * As explained at length in bt_right_page_check_scankey(),
1724 : : * there is a known !readonly race that could account for
1725 : : * apparent violation of invariant, which we must check for
1726 : : * before actually proceeding with raising error. Our canary
1727 : : * condition is that target page was deleted.
1728 : : */
3204 andres@anarazel.de 1729 [ # # ]:UBC 0 : if (!state->readonly)
1730 : : {
1731 : : /* Get fresh copy of target page */
1732 : 0 : state->target = palloc_btree_page(state, state->targetblock);
1733 : : /* Note that we deliberately do not update target LSN */
1355 michael@paquier.xyz 1734 : 0 : topaque = BTPageGetOpaque(state->target);
1735 : :
1736 : : /*
1737 : : * All !readonly checks now performed; just return
1738 : : */
3204 andres@anarazel.de 1739 [ # # ]: 0 : if (P_IGNORE(topaque))
1740 : 0 : return;
1741 : : }
1742 : :
1743 [ # # ]: 0 : ereport(ERROR,
1744 : : (errcode(ERRCODE_INDEX_CORRUPTED),
1745 : : errmsg("cross page item order invariant violated for index \"%s\"",
1746 : : RelationGetRelationName(state->rel)),
1747 : : errdetail_internal("Last item on page tid=(%u,%u) page lsn=%X/%08X.",
1748 : : state->targetblock, offset,
1749 : : LSN_FORMAT_ARGS(state->targetlsn))));
1750 : : }
1751 : :
1752 : : /*
1753 : : * If index has unique constraint make sure that no more than one
1754 : : * found equal items is visible.
1755 : : */
780 akorotkov@postgresql 1756 [ + + + + :CBC 9296 : if (state->checkunique && state->indexinfo->ii_Unique &&
+ + ]
572 1757 [ + - + - ]: 549 : rightkey && P_ISLEAF(topaque) && !P_RIGHTMOST(topaque))
1758 : : {
1759 : 549 : BlockNumber rightblock_number = topaque->btpo_next;
1760 : :
780 1761 [ - + ]: 549 : elog(DEBUG2, "check cross page unique condition");
1762 : :
1763 : : /*
1764 : : * Make _bt_compare compare only index keys without heap TIDs.
1765 : : * rightkey->scantid is modified destructively but it is ok
1766 : : * for it is not used later.
1767 : : */
1768 : 549 : rightkey->scantid = NULL;
1769 : :
1770 : : /* The first key on the next page is the same */
506 1771 [ + + ]: 549 : if (_bt_compare(state->rel, rightkey, state->target, max) == 0 &&
1772 [ - + ]: 7 : !rightkey->anynullkeys)
1773 : : {
1774 : : Page rightpage;
1775 : :
1776 : : /*
1777 : : * Do the bt_entry_unique_check() call if it was
1778 : : * postponed.
1779 : : */
506 akorotkov@postgresql 1780 [ # # ]:UBC 0 : if (!unique_checked)
1781 : 0 : bt_entry_unique_check(state, itup, state->targetblock,
1782 : : offset, &lVis);
1783 : :
780 1784 [ # # ]: 0 : elog(DEBUG2, "cross page equal keys");
572 1785 : 0 : rightpage = palloc_btree_page(state,
1786 : : rightblock_number);
1787 : 0 : topaque = BTPageGetOpaque(rightpage);
1788 : :
1789 [ # # ]: 0 : if (P_IGNORE(topaque))
1790 : : {
569 1791 : 0 : pfree(rightpage);
1792 : 0 : break;
1793 : : }
1794 : :
1795 [ # # ]: 0 : if (unlikely(!P_ISLEAF(topaque)))
1796 [ # # ]: 0 : ereport(ERROR,
1797 : : (errcode(ERRCODE_INDEX_CORRUPTED),
1798 : : errmsg("right block of leaf block is non-leaf for index \"%s\"",
1799 : : RelationGetRelationName(state->rel)),
1800 : : errdetail_internal("Block=%u page lsn=%X/%08X.",
1801 : : state->targetblock,
1802 : : LSN_FORMAT_ARGS(state->targetlsn))));
1803 : :
780 1804 : 0 : itemid = PageGetItemIdCareful(state, rightblock_number,
1805 : : rightpage,
1806 : : rightfirstoffset);
572 1807 : 0 : itup = (IndexTuple) PageGetItem(rightpage, itemid);
1808 : :
1809 : 0 : bt_entry_unique_check(state, itup, rightblock_number, rightfirstoffset, &lVis);
1810 : :
1811 : 0 : pfree(rightpage);
1812 : : }
1813 : : }
1814 : : }
1815 : :
1816 : : /*
1817 : : * * Downlink check *
1818 : : *
1819 : : * Additional check of child items iff this is an internal page and
1820 : : * caller holds a ShareLock. This happens for every downlink (item)
1821 : : * in target excluding the negative-infinity downlink (again, this is
1822 : : * because it has no useful value to compare).
1823 : : */
3204 andres@anarazel.de 1824 [ + + + + ]:CBC 2054594 : if (!P_ISLEAF(topaque) && state->readonly)
2106 akorotkov@postgresql 1825 : 1861 : bt_child_check(state, skey, offset);
1826 : : }
1827 : :
1828 : : /*
1829 : : * Special case bt_child_highkey_check() call
1830 : : *
1831 : : * We don't pass a real downlink, but we've to finish the level
1832 : : * processing. If condition is satisfied, we've already processed all the
1833 : : * downlinks from the target level. But there still might be pages to the
1834 : : * right of the child page pointer to by our rightmost downlink. And they
1835 : : * might have missing downlinks. This final call checks for them.
1836 : : */
1837 [ + + + + : 9298 : if (!P_ISLEAF(topaque) && P_RIGHTMOST(topaque) && state->readonly)
+ + ]
1838 : : {
1839 : 11 : bt_child_highkey_check(state, InvalidOffsetNumber,
1840 : : NULL, topaque->btpo_level);
1841 : : }
1842 : : }
1843 : :
1844 : : /*
1845 : : * Return a scankey for an item on page to right of current target (or the
1846 : : * first non-ignorable page), sufficient to check ordering invariant on last
1847 : : * item in current target page. Returned scankey relies on local memory
1848 : : * allocated for the child page, which caller cannot pfree(). Caller's memory
1849 : : * context should be reset between calls here.
1850 : : *
1851 : : * This is the first data item, and so all adjacent items are checked against
1852 : : * their immediate sibling item (which may be on a sibling page, or even a
1853 : : * "cousin" page at parent boundaries where target's rightlink points to page
1854 : : * with different parent page). If no such valid item is available, return
1855 : : * NULL instead.
1856 : : *
1857 : : * Note that !readonly callers must reverify that target page has not
1858 : : * been concurrently deleted.
1859 : : *
1860 : : * Save rightfirstoffset for detailed error message.
1861 : : */
1862 : : static BTScanInsert
780 1863 : 9296 : bt_right_page_check_scankey(BtreeCheckState *state, OffsetNumber *rightfirstoffset)
1864 : : {
1865 : : BTPageOpaque opaque;
1866 : : ItemId rightitem;
1867 : : IndexTuple firstitup;
1868 : : BlockNumber targetnext;
1869 : : Page rightpage;
1870 : : OffsetNumber nline;
1871 : :
1872 : : /* Determine target's next block number */
1355 michael@paquier.xyz 1873 : 9296 : opaque = BTPageGetOpaque(state->target);
1874 : :
1875 : : /* If target is already rightmost, no right sibling; nothing to do here */
3204 andres@anarazel.de 1876 [ + + ]: 9296 : if (P_RIGHTMOST(opaque))
1877 : 2493 : return NULL;
1878 : :
1879 : : /*
1880 : : * General notes on concurrent page splits and page deletion:
1881 : : *
1882 : : * Routines like _bt_search() don't require *any* page split interlock
1883 : : * when descending the tree, including something very light like a buffer
1884 : : * pin. That's why it's okay that we don't either. This avoidance of any
1885 : : * need to "couple" buffer locks is the raison d' etre of the Lehman & Yao
1886 : : * algorithm, in fact.
1887 : : *
1888 : : * That leaves deletion. A deleted page won't actually be recycled by
1889 : : * VACUUM early enough for us to fail to at least follow its right link
1890 : : * (or left link, or downlink) and find its sibling, because recycling
1891 : : * does not occur until no possible index scan could land on the page.
1892 : : * Index scans can follow links with nothing more than their snapshot as
1893 : : * an interlock and be sure of at least that much. (See page
1894 : : * recycling/"visible to everyone" notes in nbtree README.)
1895 : : *
1896 : : * Furthermore, it's okay if we follow a rightlink and find a half-dead or
1897 : : * dead (ignorable) page one or more times. There will either be a
1898 : : * further right link to follow that leads to a live page before too long
1899 : : * (before passing by parent's rightmost child), or we will find the end
1900 : : * of the entire level instead (possible when parent page is itself the
1901 : : * rightmost on its level).
1902 : : */
1903 : 6803 : targetnext = opaque->btpo_next;
1904 : : for (;;)
1905 : : {
1906 [ - + ]: 6803 : CHECK_FOR_INTERRUPTS();
1907 : :
1908 : 6803 : rightpage = palloc_btree_page(state, targetnext);
1355 michael@paquier.xyz 1909 : 6803 : opaque = BTPageGetOpaque(rightpage);
1910 : :
3204 andres@anarazel.de 1911 [ - + - - ]: 6803 : if (!P_IGNORE(opaque) || P_RIGHTMOST(opaque))
1912 : : break;
1913 : :
1914 : : /*
1915 : : * We landed on a deleted or half-dead sibling page. Step right until
1916 : : * we locate a live sibling page.
1917 : : */
1736 pg@bowt.ie 1918 [ # # ]:UBC 0 : ereport(DEBUG2,
1919 : : (errcode(ERRCODE_NO_DATA),
1920 : : errmsg_internal("level %u sibling page in block %u of index \"%s\" was found deleted or half dead",
1921 : : opaque->btpo_level, targetnext, RelationGetRelationName(state->rel)),
1922 : : errdetail_internal("Deleted page found when building scankey from right sibling.")));
1923 : :
1924 : 0 : targetnext = opaque->btpo_next;
1925 : :
1926 : : /* Be slightly more pro-active in freeing this memory, just in case */
3204 andres@anarazel.de 1927 : 0 : pfree(rightpage);
1928 : : }
1929 : :
1930 : : /*
1931 : : * No ShareLock held case -- why it's safe to proceed.
1932 : : *
1933 : : * Problem:
1934 : : *
1935 : : * We must avoid false positive reports of corruption when caller treats
1936 : : * item returned here as an upper bound on target's last item. In
1937 : : * general, false positives are disallowed. Avoiding them here when
1938 : : * caller is !readonly is subtle.
1939 : : *
1940 : : * A concurrent page deletion by VACUUM of the target page can result in
1941 : : * the insertion of items on to this right sibling page that would
1942 : : * previously have been inserted on our target page. There might have
1943 : : * been insertions that followed the target's downlink after it was made
1944 : : * to point to right sibling instead of target by page deletion's first
1945 : : * phase. The inserters insert items that would belong on target page.
1946 : : * This race is very tight, but it's possible. This is our only problem.
1947 : : *
1948 : : * Non-problems:
1949 : : *
1950 : : * We are not hindered by a concurrent page split of the target; we'll
1951 : : * never land on the second half of the page anyway. A concurrent split
1952 : : * of the right page will also not matter, because the first data item
1953 : : * remains the same within the left half, which we'll reliably land on. If
1954 : : * we had to skip over ignorable/deleted pages, it cannot matter because
1955 : : * their key space has already been atomically merged with the first
1956 : : * non-ignorable page we eventually find (doesn't matter whether the page
1957 : : * we eventually find is a true sibling or a cousin of target, which we go
1958 : : * into below).
1959 : : *
1960 : : * Solution:
1961 : : *
1962 : : * Caller knows that it should reverify that target is not ignorable
1963 : : * (half-dead or deleted) when cross-page sibling item comparison appears
1964 : : * to indicate corruption (invariant fails). This detects the single race
1965 : : * condition that exists for caller. This is correct because the
1966 : : * continued existence of target block as non-ignorable (not half-dead or
1967 : : * deleted) implies that target page was not merged into from the right by
1968 : : * deletion; the key space at or after target never moved left. Target's
1969 : : * parent either has the same downlink to target as before, or a <
1970 : : * downlink due to deletion at the left of target. Target either has the
1971 : : * same highkey as before, or a highkey < before when there is a page
1972 : : * split. (The rightmost concurrently-split-from-target-page page will
1973 : : * still have the same highkey as target was originally found to have,
1974 : : * which for our purposes is equivalent to target's highkey itself never
1975 : : * changing, since we reliably skip over
1976 : : * concurrently-split-from-target-page pages.)
1977 : : *
1978 : : * In simpler terms, we allow that the key space of the target may expand
1979 : : * left (the key space can move left on the left side of target only), but
1980 : : * the target key space cannot expand right and get ahead of us without
1981 : : * our detecting it. The key space of the target cannot shrink, unless it
1982 : : * shrinks to zero due to the deletion of the original page, our canary
1983 : : * condition. (To be very precise, we're a bit stricter than that because
1984 : : * it might just have been that the target page split and only the
1985 : : * original target page was deleted. We can be more strict, just not more
1986 : : * lax.)
1987 : : *
1988 : : * Top level tree walk caller moves on to next page (makes it the new
1989 : : * target) following recovery from this race. (cf. The rationale for
1990 : : * child/downlink verification needing a ShareLock within
1991 : : * bt_child_check(), where page deletion is also the main source of
1992 : : * trouble.)
1993 : : *
1994 : : * Note that it doesn't matter if right sibling page here is actually a
1995 : : * cousin page, because in order for the key space to be readjusted in a
1996 : : * way that causes us issues in next level up (guiding problematic
1997 : : * concurrent insertions to the cousin from the grandparent rather than to
1998 : : * the sibling from the parent), there'd have to be page deletion of
1999 : : * target's parent page (affecting target's parent's downlink in target's
2000 : : * grandparent page). Internal page deletion only occurs when there are
2001 : : * no child pages (they were all fully deleted), and caller is checking
2002 : : * that the target's parent has at least one non-deleted (so
2003 : : * non-ignorable) child: the target page. (Note that the first phase of
2004 : : * deletion atomically marks the page to be deleted half-dead/ignorable at
2005 : : * the same time downlink in its parent is removed, so caller will
2006 : : * definitely not fail to detect that this happened.)
2007 : : *
2008 : : * This trick is inspired by the method backward scans use for dealing
2009 : : * with concurrent page splits; concurrent page deletion is a problem that
2010 : : * similarly receives special consideration sometimes (it's possible that
2011 : : * the backwards scan will re-read its "original" block after failing to
2012 : : * find a right-link to it, having already moved in the opposite direction
2013 : : * (right/"forwards") a few times to try to locate one). Just like us,
2014 : : * that happens only to determine if there was a concurrent page deletion
2015 : : * of a reference page, and just like us if there was a page deletion of
2016 : : * that reference page it means we can move on from caring about the
2017 : : * reference page. See the nbtree README for a full description of how
2018 : : * that works.
2019 : : */
3204 andres@anarazel.de 2020 :CBC 6803 : nline = PageGetMaxOffsetNumber(rightpage);
2021 : :
2022 : : /*
2023 : : * Get first data item, if any
2024 : : */
2025 [ + + + + : 6803 : if (P_ISLEAF(opaque) && nline >= P_FIRSTDATAKEY(opaque))
+ - ]
2026 : : {
2027 : : /* Return first data item (if any) */
2427 pg@bowt.ie 2028 : 6801 : rightitem = PageGetItemIdCareful(state, targetnext, rightpage,
2029 [ + + ]: 6801 : P_FIRSTDATAKEY(opaque));
780 akorotkov@postgresql 2030 [ + + ]: 6801 : *rightfirstoffset = P_FIRSTDATAKEY(opaque);
2031 : : }
3204 andres@anarazel.de 2032 [ + - + - ]: 4 : else if (!P_ISLEAF(opaque) &&
2033 [ + - ]: 2 : nline >= OffsetNumberNext(P_FIRSTDATAKEY(opaque)))
2034 : : {
2035 : : /*
2036 : : * Return first item after the internal page's "negative infinity"
2037 : : * item
2038 : : */
2427 pg@bowt.ie 2039 : 2 : rightitem = PageGetItemIdCareful(state, targetnext, rightpage,
2040 [ + - ]: 2 : OffsetNumberNext(P_FIRSTDATAKEY(opaque)));
2041 : : }
2042 : : else
2043 : : {
2044 : : /*
2045 : : * No first item. Page is probably empty leaf page, but it's also
2046 : : * possible that it's an internal page with only a negative infinity
2047 : : * item.
2048 : : */
1736 pg@bowt.ie 2049 [ # # # # ]:UBC 0 : ereport(DEBUG2,
2050 : : (errcode(ERRCODE_NO_DATA),
2051 : : errmsg_internal("%s block %u of index \"%s\" has no first data item",
2052 : : P_ISLEAF(opaque) ? "leaf" : "internal", targetnext,
2053 : : RelationGetRelationName(state->rel))));
3204 andres@anarazel.de 2054 : 0 : return NULL;
2055 : : }
2056 : :
2057 : : /*
2058 : : * Return first real item scankey. Note that this relies on right page
2059 : : * memory remaining allocated.
2060 : : */
2463 pg@bowt.ie 2061 :CBC 6803 : firstitup = (IndexTuple) PageGetItem(rightpage, rightitem);
920 2062 : 6803 : return bt_mkscankey_pivotsearch(state->rel, firstitup);
2063 : : }
2064 : :
2065 : : /*
2066 : : * Check if two tuples are binary identical except the block number. So,
2067 : : * this function is capable to compare pivot keys on different levels.
2068 : : */
2069 : : static bool
1917 2070 : 1862 : bt_pivot_tuple_identical(bool heapkeyspace, IndexTuple itup1, IndexTuple itup2)
2071 : : {
2106 akorotkov@postgresql 2072 [ - + ]: 1862 : if (IndexTupleSize(itup1) != IndexTupleSize(itup2))
2106 akorotkov@postgresql 2073 :UBC 0 : return false;
2074 : :
1917 pg@bowt.ie 2075 [ + - ]:CBC 1862 : if (heapkeyspace)
2076 : : {
2077 : : /*
2078 : : * Offset number will contain important information in heapkeyspace
2079 : : * indexes: the number of attributes left in the pivot tuple following
2080 : : * suffix truncation. Don't skip over it (compare it too).
2081 : : */
2082 [ - + ]: 1862 : if (memcmp(&itup1->t_tid.ip_posid, &itup2->t_tid.ip_posid,
2083 : 1862 : IndexTupleSize(itup1) -
2084 : : offsetof(ItemPointerData, ip_posid)) != 0)
1917 pg@bowt.ie 2085 :UBC 0 : return false;
2086 : : }
2087 : : else
2088 : : {
2089 : : /*
2090 : : * Cannot rely on offset number field having consistent value across
2091 : : * levels on pg_upgrade'd !heapkeyspace indexes. Compare contents of
2092 : : * tuple starting from just after item pointer (i.e. after block
2093 : : * number and offset number).
2094 : : */
2095 [ # # ]: 0 : if (memcmp(&itup1->t_info, &itup2->t_info,
2096 : 0 : IndexTupleSize(itup1) -
2097 : : offsetof(IndexTupleData, t_info)) != 0)
2098 : 0 : return false;
2099 : : }
2100 : :
2106 akorotkov@postgresql 2101 :CBC 1862 : return true;
2102 : : }
2103 : :
2104 : : /*---
2105 : : * Check high keys on the child level. Traverse rightlinks from previous
2106 : : * downlink to the current one. Check that there are no intermediate pages
2107 : : * with missing downlinks.
2108 : : *
2109 : : * If 'loaded_child' is given, it's assumed to be the page pointed to by the
2110 : : * downlink referenced by 'downlinkoffnum' of the target page.
2111 : : *
2112 : : * Basically this function is called for each target downlink and checks two
2113 : : * invariants:
2114 : : *
2115 : : * 1) You can reach the next child from previous one via rightlinks;
2116 : : * 2) Each child high key have matching pivot key on target level.
2117 : : *
2118 : : * Consider the sample tree picture.
2119 : : *
2120 : : * 1
2121 : : * / \
2122 : : * 2 <-> 3
2123 : : * / \ / \
2124 : : * 4 <> 5 <> 6 <> 7 <> 8
2125 : : *
2126 : : * This function will be called for blocks 4, 5, 6 and 8. Consider what is
2127 : : * happening for each function call.
2128 : : *
2129 : : * - The function call for block 4 initializes data structure and matches high
2130 : : * key of block 4 to downlink's pivot key of block 2.
2131 : : * - The high key of block 5 is matched to the high key of block 2.
2132 : : * - The block 6 has an incomplete split flag set, so its high key isn't
2133 : : * matched to anything.
2134 : : * - The function call for block 8 checks that block 8 can be found while
2135 : : * following rightlinks from block 6. The high key of block 7 will be
2136 : : * matched to downlink's pivot key in block 3.
2137 : : *
2138 : : * There is also final call of this function, which checks that there is no
2139 : : * missing downlinks for children to the right of the child referenced by
2140 : : * rightmost downlink in target level.
2141 : : */
2142 : : static void
2143 : 1884 : bt_child_highkey_check(BtreeCheckState *state,
2144 : : OffsetNumber target_downlinkoffnum,
2145 : : Page loaded_child,
2146 : : uint32 target_level)
2147 : : {
2148 : 1884 : BlockNumber blkno = state->prevrightlink;
2149 : : Page page;
2150 : : BTPageOpaque opaque;
2151 : 1884 : bool rightsplit = state->previncompletesplit;
2152 : 1884 : bool first = true;
2153 : : ItemId itemid;
2154 : : IndexTuple itup;
2155 : : BlockNumber downlink;
2156 : :
2157 [ + + + - : 1884 : if (OffsetNumberIsValid(target_downlinkoffnum))
+ + ]
2158 : : {
2159 : 1873 : itemid = PageGetItemIdCareful(state, state->targetblock,
2160 : : state->target, target_downlinkoffnum);
2161 : 1873 : itup = (IndexTuple) PageGetItem(state->target, itemid);
2162 : 1873 : downlink = BTreeTupleGetDownLink(itup);
2163 : : }
2164 : : else
2165 : : {
2166 : 11 : downlink = P_NONE;
2167 : : }
2168 : :
2169 : : /*
2170 : : * If no previous rightlink is memorized for current level just below
2171 : : * target page's level, we are about to start from the leftmost page. We
2172 : : * can't follow rightlinks from previous page, because there is no
2173 : : * previous page. But we still can match high key.
2174 : : *
2175 : : * So we initialize variables for the loop above like there is previous
2176 : : * page referencing current child. Also we imply previous page to not
2177 : : * have incomplete split flag, that would make us require downlink for
2178 : : * current child. That's correct, because leftmost page on the level
2179 : : * should always have parent downlink.
2180 : : */
2181 [ + + ]: 1884 : if (!BlockNumberIsValid(blkno))
2182 : : {
2183 : 11 : blkno = downlink;
2184 : 11 : rightsplit = false;
2185 : : }
2186 : :
2187 : : /* Move to the right on the child level */
2188 : : while (true)
2189 : : {
2190 : : /*
2191 : : * Did we traverse the whole tree level and this is check for pages to
2192 : : * the right of rightmost downlink?
2193 : : */
2194 [ + + + - ]: 1884 : if (blkno == P_NONE && downlink == P_NONE)
2195 : : {
2196 : 11 : state->prevrightlink = InvalidBlockNumber;
2197 : 11 : state->previncompletesplit = false;
2198 : 11 : return;
2199 : : }
2200 : :
2201 : : /* Did we traverse the whole tree level and don't find next downlink? */
2202 [ - + ]: 1873 : if (blkno == P_NONE)
2106 akorotkov@postgresql 2203 [ # # ]:UBC 0 : ereport(ERROR,
2204 : : (errcode(ERRCODE_INDEX_CORRUPTED),
2205 : : errmsg("can't traverse from downlink %u to downlink %u of index \"%s\"",
2206 : : state->prevrightlink, downlink,
2207 : : RelationGetRelationName(state->rel))));
2208 : :
2209 : : /* Load page contents */
2106 akorotkov@postgresql 2210 [ + - + + ]:CBC 1873 : if (blkno == downlink && loaded_child)
2211 : 1861 : page = loaded_child;
2212 : : else
2213 : 12 : page = palloc_btree_page(state, blkno);
2214 : :
1355 michael@paquier.xyz 2215 : 1873 : opaque = BTPageGetOpaque(page);
2216 : :
2217 : : /* The first page we visit at the level should be leftmost */
778 noah@leadboat.com 2218 [ + - + + ]: 1873 : if (first && !BlockNumberIsValid(state->prevrightlink) &&
2219 [ - + ]: 11 : !bt_leftmost_ignoring_half_dead(state, blkno, opaque))
2106 akorotkov@postgresql 2220 [ # # ]:UBC 0 : ereport(ERROR,
2221 : : (errcode(ERRCODE_INDEX_CORRUPTED),
2222 : : errmsg("the first child of leftmost target page is not leftmost of its level in index \"%s\"",
2223 : : RelationGetRelationName(state->rel)),
2224 : : errdetail_internal("Target block=%u child block=%u target page lsn=%X/%08X.",
2225 : : state->targetblock, blkno,
2226 : : LSN_FORMAT_ARGS(state->targetlsn))));
2227 : :
2228 : : /* Do level sanity check */
1756 pg@bowt.ie 2229 [ - + - - ]:CBC 1873 : if ((!P_ISDELETED(opaque) || P_HAS_FULLXID(opaque)) &&
2230 [ - + ]: 1873 : opaque->btpo_level != target_level - 1)
2106 akorotkov@postgresql 2231 [ # # ]:UBC 0 : ereport(ERROR,
2232 : : (errcode(ERRCODE_INDEX_CORRUPTED),
2233 : : errmsg("block found while following rightlinks from child of index \"%s\" has invalid level",
2234 : : RelationGetRelationName(state->rel)),
2235 : : errdetail_internal("Block pointed to=%u expected level=%u level in pointed to block=%u.",
2236 : : blkno, target_level - 1, opaque->btpo_level)));
2237 : :
2238 : : /* Try to detect circular links */
2106 akorotkov@postgresql 2239 [ - + - - :CBC 1873 : if ((!first && blkno == state->prevrightlink) || blkno == opaque->btpo_prev)
- + ]
2106 akorotkov@postgresql 2240 [ # # ]:UBC 0 : ereport(ERROR,
2241 : : (errcode(ERRCODE_INDEX_CORRUPTED),
2242 : : errmsg("circular link chain found in block %u of index \"%s\"",
2243 : : blkno, RelationGetRelationName(state->rel))));
2244 : :
2106 akorotkov@postgresql 2245 [ - + - - ]:CBC 1873 : if (blkno != downlink && !P_IGNORE(opaque))
2246 : : {
2247 : : /* blkno probably has missing parent downlink */
2106 akorotkov@postgresql 2248 :UBC 0 : bt_downlink_missing_check(state, rightsplit, blkno, page);
2249 : : }
2250 : :
2106 akorotkov@postgresql 2251 :CBC 1873 : rightsplit = P_INCOMPLETE_SPLIT(opaque);
2252 : :
2253 : : /*
2254 : : * If we visit page with high key, check that it is equal to the
2255 : : * target key next to corresponding downlink.
2256 : : */
14 heikki.linnakangas@i 2257 [ + - + + : 1873 : if (!rightsplit && !P_RIGHTMOST(opaque) && !P_ISHALFDEAD(opaque))
+ - ]
2258 : : {
2259 : : BTPageOpaque topaque;
2260 : : IndexTuple highkey;
2261 : : OffsetNumber pivotkey_offset;
2262 : :
2263 : : /* Get high key */
2106 akorotkov@postgresql 2264 : 1862 : itemid = PageGetItemIdCareful(state, blkno, page, P_HIKEY);
2265 : 1862 : highkey = (IndexTuple) PageGetItem(page, itemid);
2266 : :
2267 : : /*
2268 : : * There might be two situations when we examine high key. If
2269 : : * current child page is referenced by given target downlink, we
2270 : : * should look to the next offset number for matching key from
2271 : : * target page.
2272 : : *
2273 : : * Alternatively, we're following rightlinks somewhere in the
2274 : : * middle between page referenced by previous target's downlink
2275 : : * and the page referenced by current target's downlink. If
2276 : : * current child page hasn't incomplete split flag set, then its
2277 : : * high key should match to the target's key of current offset
2278 : : * number. This happens when a previous call here (to
2279 : : * bt_child_highkey_check()) found an incomplete split, and we
2280 : : * reach a right sibling page without a downlink -- the right
2281 : : * sibling page's high key still needs to be matched to a
2282 : : * separator key on the parent/target level.
2283 : : *
2284 : : * Don't apply OffsetNumberNext() to target_downlinkoffnum when we
2285 : : * already had to step right on the child level. Our traversal of
2286 : : * the child level must try to move in perfect lockstep behind (to
2287 : : * the left of) the target/parent level traversal.
2288 : : */
2289 [ + - ]: 1862 : if (blkno == downlink)
2290 : 1862 : pivotkey_offset = OffsetNumberNext(target_downlinkoffnum);
2291 : : else
2106 akorotkov@postgresql 2292 :UBC 0 : pivotkey_offset = target_downlinkoffnum;
2293 : :
1355 michael@paquier.xyz 2294 :CBC 1862 : topaque = BTPageGetOpaque(state->target);
2295 : :
2106 akorotkov@postgresql 2296 [ + - ]: 1862 : if (!offset_is_negative_infinity(topaque, pivotkey_offset))
2297 : : {
2298 : : /*
2299 : : * If we're looking for the next pivot tuple in target page,
2300 : : * but there is no more pivot tuples, then we should match to
2301 : : * high key instead.
2302 : : */
2303 [ + + ]: 1862 : if (pivotkey_offset > PageGetMaxOffsetNumber(state->target))
2304 : : {
2305 [ - + ]: 1 : if (P_RIGHTMOST(topaque))
2106 akorotkov@postgresql 2306 [ # # ]:UBC 0 : ereport(ERROR,
2307 : : (errcode(ERRCODE_INDEX_CORRUPTED),
2308 : : errmsg("child high key is greater than rightmost pivot key on target level in index \"%s\"",
2309 : : RelationGetRelationName(state->rel)),
2310 : : errdetail_internal("Target block=%u child block=%u target page lsn=%X/%08X.",
2311 : : state->targetblock, blkno,
2312 : : LSN_FORMAT_ARGS(state->targetlsn))));
2106 akorotkov@postgresql 2313 :CBC 1 : pivotkey_offset = P_HIKEY;
2314 : : }
2315 : 1862 : itemid = PageGetItemIdCareful(state, state->targetblock,
2316 : : state->target, pivotkey_offset);
2317 : 1862 : itup = (IndexTuple) PageGetItem(state->target, itemid);
2318 : : }
2319 : : else
2320 : : {
2321 : : /*
2322 : : * We cannot try to match child's high key to a negative
2323 : : * infinity key in target, since there is nothing to compare.
2324 : : * However, it's still possible to match child's high key
2325 : : * outside of target page. The reason why we're are is that
2326 : : * bt_child_highkey_check() was previously called for the
2327 : : * cousin page of 'loaded_child', which is incomplete split.
2328 : : * So, now we traverse to the right of that cousin page and
2329 : : * current child level page under consideration still belongs
2330 : : * to the subtree of target's left sibling. Thus, we need to
2331 : : * match child's high key to its left uncle page high key.
2332 : : * Thankfully we saved it, it's called a "low key" of target
2333 : : * page.
2334 : : */
2106 akorotkov@postgresql 2335 [ # # ]:UBC 0 : if (!state->lowkey)
2336 [ # # ]: 0 : ereport(ERROR,
2337 : : (errcode(ERRCODE_INDEX_CORRUPTED),
2338 : : errmsg("can't find left sibling high key in index \"%s\"",
2339 : : RelationGetRelationName(state->rel)),
2340 : : errdetail_internal("Target block=%u child block=%u target page lsn=%X/%08X.",
2341 : : state->targetblock, blkno,
2342 : : LSN_FORMAT_ARGS(state->targetlsn))));
2343 : 0 : itup = state->lowkey;
2344 : : }
2345 : :
1917 pg@bowt.ie 2346 [ - + ]:CBC 1862 : if (!bt_pivot_tuple_identical(state->heapkeyspace, highkey, itup))
2347 : : {
2106 akorotkov@postgresql 2348 [ # # ]:UBC 0 : ereport(ERROR,
2349 : : (errcode(ERRCODE_INDEX_CORRUPTED),
2350 : : errmsg("mismatch between parent key and child high key in index \"%s\"",
2351 : : RelationGetRelationName(state->rel)),
2352 : : errdetail_internal("Target block=%u child block=%u target page lsn=%X/%08X.",
2353 : : state->targetblock, blkno,
2354 : : LSN_FORMAT_ARGS(state->targetlsn))));
2355 : : }
2356 : : }
2357 : :
2358 : : /* Exit if we already found next downlink */
2106 akorotkov@postgresql 2359 [ + - ]:CBC 1873 : if (blkno == downlink)
2360 : : {
2361 : 1873 : state->prevrightlink = opaque->btpo_next;
2362 : 1873 : state->previncompletesplit = rightsplit;
2363 : 1873 : return;
2364 : : }
2365 : :
2366 : : /* Traverse to the next page using rightlink */
2106 akorotkov@postgresql 2367 :UBC 0 : blkno = opaque->btpo_next;
2368 : :
2369 : : /* Free page contents if it's allocated by us */
2370 [ # # ]: 0 : if (page != loaded_child)
2371 : 0 : pfree(page);
2372 : 0 : first = false;
2373 : : }
2374 : : }
2375 : :
2376 : : /*
2377 : : * Checks one of target's downlink against its child page.
2378 : : *
2379 : : * Conceptually, the target page continues to be what is checked here. The
2380 : : * target block is still blamed in the event of finding an invariant violation.
2381 : : * The downlink insertion into the target is probably where any problem raised
2382 : : * here arises, and there is no such thing as a parent link, so doing the
2383 : : * verification this way around is much more practical.
2384 : : *
2385 : : * This function visits child page and it's sequentially called for each
2386 : : * downlink of target page. Assuming this we also check downlink connectivity
2387 : : * here in order to save child page visits.
2388 : : */
2389 : : static void
2106 akorotkov@postgresql 2390 :CBC 1861 : bt_child_check(BtreeCheckState *state, BTScanInsert targetkey,
2391 : : OffsetNumber downlinkoffnum)
2392 : : {
2393 : : ItemId itemid;
2394 : : IndexTuple itup;
2395 : : BlockNumber childblock;
2396 : : OffsetNumber offset;
2397 : : OffsetNumber maxoffset;
2398 : : Page child;
2399 : : BTPageOpaque copaque;
2400 : : BTPageOpaque topaque;
2401 : :
2402 : 1861 : itemid = PageGetItemIdCareful(state, state->targetblock,
2403 : : state->target, downlinkoffnum);
2404 : 1861 : itup = (IndexTuple) PageGetItem(state->target, itemid);
2405 : 1861 : childblock = BTreeTupleGetDownLink(itup);
2406 : :
2407 : : /*
2408 : : * Caller must have ShareLock on target relation, because of
2409 : : * considerations around page deletion by VACUUM.
2410 : : *
2411 : : * NB: In general, page deletion deletes the right sibling's downlink, not
2412 : : * the downlink of the page being deleted; the deleted page's downlink is
2413 : : * reused for its sibling. The key space is thereby consolidated between
2414 : : * the deleted page and its right sibling. (We cannot delete a parent
2415 : : * page's rightmost child unless it is the last child page, and we intend
2416 : : * to also delete the parent itself.)
2417 : : *
2418 : : * If this verification happened without a ShareLock, the following race
2419 : : * condition could cause false positives:
2420 : : *
2421 : : * In general, concurrent page deletion might occur, including deletion of
2422 : : * the left sibling of the child page that is examined here. If such a
2423 : : * page deletion were to occur, closely followed by an insertion into the
2424 : : * newly expanded key space of the child, a window for the false positive
2425 : : * opens up: the stale parent/target downlink originally followed to get
2426 : : * to the child legitimately ceases to be a lower bound on all items in
2427 : : * the page, since the key space was concurrently expanded "left".
2428 : : * (Insertion followed the "new" downlink for the child, not our now-stale
2429 : : * downlink, which was concurrently physically removed in target/parent as
2430 : : * part of deletion's first phase.)
2431 : : *
2432 : : * While we use various techniques elsewhere to perform cross-page
2433 : : * verification for !readonly callers, a similar trick seems difficult
2434 : : * here. The tricks used by bt_recheck_sibling_links and by
2435 : : * bt_right_page_check_scankey both involve verification of a same-level,
2436 : : * cross-sibling invariant. Cross-level invariants are far more squishy,
2437 : : * though. The nbtree REDO routines do not actually couple buffer locks
2438 : : * across levels during page splits, so making any cross-level check work
2439 : : * reliably in !readonly mode may be impossible.
2440 : : */
3204 andres@anarazel.de 2441 [ - + ]: 1861 : Assert(state->readonly);
2442 : :
2443 : : /*
2444 : : * Verify child page has the downlink key from target page (its parent) as
2445 : : * a lower bound; downlink must be strictly less than all keys on the
2446 : : * page.
2447 : : *
2448 : : * Check all items, rather than checking just the first and trusting that
2449 : : * the operator class obeys the transitive law.
2450 : : */
1355 michael@paquier.xyz 2451 : 1861 : topaque = BTPageGetOpaque(state->target);
3204 andres@anarazel.de 2452 : 1861 : child = palloc_btree_page(state, childblock);
1355 michael@paquier.xyz 2453 : 1861 : copaque = BTPageGetOpaque(child);
3204 andres@anarazel.de 2454 : 1861 : maxoffset = PageGetMaxOffsetNumber(child);
2455 : :
2456 : : /*
2457 : : * Since we've already loaded the child block, combine this check with
2458 : : * check for downlink connectivity.
2459 : : */
2106 akorotkov@postgresql 2460 : 1861 : bt_child_highkey_check(state, downlinkoffnum,
2461 : : child, topaque->btpo_level);
2462 : :
2463 : : /*
2464 : : * Since there cannot be a concurrent VACUUM operation in readonly mode,
2465 : : * and since a page has no links within other pages (siblings and parent)
2466 : : * once it is marked fully deleted, it should be impossible to land on a
2467 : : * fully deleted page.
2468 : : *
2469 : : * It does not quite make sense to enforce that the page cannot even be
2470 : : * half-dead, despite the fact the downlink is modified at the same stage
2471 : : * that the child leaf page is marked half-dead. That's incorrect because
2472 : : * there may occasionally be multiple downlinks from a chain of pages
2473 : : * undergoing deletion, where multiple successive calls are made to
2474 : : * _bt_unlink_halfdead_page() by VACUUM before it can finally safely mark
2475 : : * the leaf page as fully dead. While _bt_mark_page_halfdead() usually
2476 : : * removes the downlink to the leaf page that is marked half-dead, that's
2477 : : * not guaranteed, so it's possible we'll land on a half-dead page with a
2478 : : * downlink due to an interrupted multi-level page deletion.
2479 : : *
2480 : : * We go ahead with our checks if the child page is half-dead. It's safe
2481 : : * to do so because we do not test the child's high key, so it does not
2482 : : * matter that the original high key will have been replaced by a dummy
2483 : : * truncated high key within _bt_mark_page_halfdead(). All other page
2484 : : * items are left intact on a half-dead page, so there is still something
2485 : : * to test.
2486 : : */
2792 teodor@sigaev.ru 2487 [ - + ]: 1861 : if (P_ISDELETED(copaque))
2792 teodor@sigaev.ru 2488 [ # # ]:UBC 0 : ereport(ERROR,
2489 : : (errcode(ERRCODE_INDEX_CORRUPTED),
2490 : : errmsg("downlink to deleted page found in index \"%s\"",
2491 : : RelationGetRelationName(state->rel)),
2492 : : errdetail_internal("Parent block=%u child block=%u parent page lsn=%X/%08X.",
2493 : : state->targetblock, childblock,
2494 : : LSN_FORMAT_ARGS(state->targetlsn))));
2495 : :
3204 andres@anarazel.de 2496 [ + + ]:CBC 1861 : for (offset = P_FIRSTDATAKEY(copaque);
2497 [ + + ]: 600350 : offset <= maxoffset;
2498 : 598489 : offset = OffsetNumberNext(offset))
2499 : : {
2500 : : /*
2501 : : * Skip comparison of target page key against "negative infinity"
2502 : : * item, if any. Checking it would indicate that it's not a strict
2503 : : * lower bound, but that's only because of the hard-coding for
2504 : : * negative infinity items within _bt_compare().
2505 : : *
2506 : : * If nbtree didn't truncate negative infinity tuples during internal
2507 : : * page splits then we'd expect child's negative infinity key to be
2508 : : * equal to the scankey/downlink from target/parent (it would be a
2509 : : * "low key" in this hypothetical scenario, and so it would still need
2510 : : * to be treated as a special case here).
2511 : : *
2512 : : * Negative infinity items can be thought of as a strict lower bound
2513 : : * that works transitively, with the last non-negative-infinity pivot
2514 : : * followed during a descent from the root as its "true" strict lower
2515 : : * bound. Only a small number of negative infinity items are truly
2516 : : * negative infinity; those that are the first items of leftmost
2517 : : * internal pages. In more general terms, a negative infinity item is
2518 : : * only negative infinity with respect to the subtree that the page is
2519 : : * at the root of.
2520 : : *
2521 : : * See also: bt_rootdescend(), which can even detect transitive
2522 : : * inconsistencies on cousin leaf pages.
2523 : : */
2524 [ + + ]: 598489 : if (offset_is_negative_infinity(copaque, offset))
2525 : 1 : continue;
2526 : :
2427 pg@bowt.ie 2527 [ - + ]: 598488 : if (!invariant_l_nontarget_offset(state, targetkey, childblock, child,
2528 : : offset))
3204 andres@anarazel.de 2529 [ # # ]:UBC 0 : ereport(ERROR,
2530 : : (errcode(ERRCODE_INDEX_CORRUPTED),
2531 : : errmsg("down-link lower bound invariant violated for index \"%s\"",
2532 : : RelationGetRelationName(state->rel)),
2533 : : errdetail_internal("Parent block=%u child index tid=(%u,%u) parent page lsn=%X/%08X.",
2534 : : state->targetblock, childblock, offset,
2535 : : LSN_FORMAT_ARGS(state->targetlsn))));
2536 : : }
2537 : :
3204 andres@anarazel.de 2538 :CBC 1861 : pfree(child);
2539 : 1861 : }
2540 : :
2541 : : /*
2542 : : * Checks if page is missing a downlink that it should have.
2543 : : *
2544 : : * A page that lacks a downlink/parent may indicate corruption. However, we
2545 : : * must account for the fact that a missing downlink can occasionally be
2546 : : * encountered in a non-corrupt index. This can be due to an interrupted page
2547 : : * split, or an interrupted multi-level page deletion (i.e. there was a hard
2548 : : * crash or an error during a page split, or while VACUUM was deleting a
2549 : : * multi-level chain of pages).
2550 : : *
2551 : : * Note that this can only be called in readonly mode, so there is no need to
2552 : : * be concerned about concurrent page splits or page deletions.
2553 : : */
2554 : : static void
2106 akorotkov@postgresql 2555 :UBC 0 : bt_downlink_missing_check(BtreeCheckState *state, bool rightsplit,
2556 : : BlockNumber blkno, Page page)
2557 : : {
1355 michael@paquier.xyz 2558 : 0 : BTPageOpaque opaque = BTPageGetOpaque(page);
2559 : : ItemId itemid;
2560 : : IndexTuple itup;
2561 : : Page child;
2562 : : BTPageOpaque copaque;
2563 : : uint32 level;
2564 : : BlockNumber childblk;
2565 : : XLogRecPtr pagelsn;
2566 : :
2106 akorotkov@postgresql 2567 [ # # ]: 0 : Assert(state->readonly);
2568 [ # # ]: 0 : Assert(!P_IGNORE(opaque));
2569 : :
2570 : : /* No next level up with downlinks to fingerprint from the true root */
2571 [ # # ]: 0 : if (P_ISROOT(opaque))
2792 teodor@sigaev.ru 2572 : 0 : return;
2573 : :
2106 akorotkov@postgresql 2574 : 0 : pagelsn = PageGetLSN(page);
2575 : :
2576 : : /*
2577 : : * Incomplete (interrupted) page splits can account for the lack of a
2578 : : * downlink. Some inserting transaction should eventually complete the
2579 : : * page split in passing, when it notices that the left sibling page is
2580 : : * P_INCOMPLETE_SPLIT().
2581 : : *
2582 : : * In general, VACUUM is not prepared for there to be no downlink to a
2583 : : * page that it deletes. This is the main reason why the lack of a
2584 : : * downlink can be reported as corruption here. It's not obvious that an
2585 : : * invalid missing downlink can result in wrong answers to queries,
2586 : : * though, since index scans that land on the child may end up
2587 : : * consistently moving right. The handling of concurrent page splits (and
2588 : : * page deletions) within _bt_moveright() cannot distinguish
2589 : : * inconsistencies that last for a moment from inconsistencies that are
2590 : : * permanent and irrecoverable.
2591 : : *
2592 : : * VACUUM isn't even prepared to delete pages that have no downlink due to
2593 : : * an incomplete page split, but it can detect and reason about that case
2594 : : * by design, so it shouldn't be taken to indicate corruption. See
2595 : : * _bt_pagedel() for full details.
2596 : : */
2597 [ # # ]: 0 : if (rightsplit)
2598 : : {
2792 teodor@sigaev.ru 2599 [ # # ]: 0 : ereport(DEBUG1,
2600 : : (errcode(ERRCODE_NO_DATA),
2601 : : errmsg_internal("harmless interrupted page split detected in index \"%s\"",
2602 : : RelationGetRelationName(state->rel)),
2603 : : errdetail_internal("Block=%u level=%u left sibling=%u page lsn=%X/%08X.",
2604 : : blkno, opaque->btpo_level,
2605 : : opaque->btpo_prev,
2606 : : LSN_FORMAT_ARGS(pagelsn))));
2607 : 0 : return;
2608 : : }
2609 : :
2610 : : /*
2611 : : * Page under check is probably the "top parent" of a multi-level page
2612 : : * deletion. We'll need to descend the subtree to make sure that
2613 : : * descendant pages are consistent with that, though.
2614 : : *
2615 : : * If the page (which must be non-ignorable) is a leaf page, then clearly
2616 : : * it can't be the top parent. The lack of a downlink is probably a
2617 : : * symptom of a broad problem that could just as easily cause
2618 : : * inconsistencies anywhere else.
2619 : : */
2106 akorotkov@postgresql 2620 [ # # ]: 0 : if (P_ISLEAF(opaque))
2792 teodor@sigaev.ru 2621 [ # # ]: 0 : ereport(ERROR,
2622 : : (errcode(ERRCODE_INDEX_CORRUPTED),
2623 : : errmsg("leaf index block lacks downlink in index \"%s\"",
2624 : : RelationGetRelationName(state->rel)),
2625 : : errdetail_internal("Block=%u page lsn=%X/%08X.",
2626 : : blkno,
2627 : : LSN_FORMAT_ARGS(pagelsn))));
2628 : :
2629 : : /* Descend from the given page, which is an internal page */
2630 [ # # ]: 0 : elog(DEBUG1, "checking for interrupted multi-level deletion due to missing downlink in index \"%s\"",
2631 : : RelationGetRelationName(state->rel));
2632 : :
1756 pg@bowt.ie 2633 : 0 : level = opaque->btpo_level;
2106 akorotkov@postgresql 2634 [ # # ]: 0 : itemid = PageGetItemIdCareful(state, blkno, page, P_FIRSTDATAKEY(opaque));
2635 : 0 : itup = (IndexTuple) PageGetItem(page, itemid);
2192 pg@bowt.ie 2636 : 0 : childblk = BTreeTupleGetDownLink(itup);
2637 : : for (;;)
2638 : : {
2792 teodor@sigaev.ru 2639 [ # # ]: 0 : CHECK_FOR_INTERRUPTS();
2640 : :
2641 : 0 : child = palloc_btree_page(state, childblk);
1355 michael@paquier.xyz 2642 : 0 : copaque = BTPageGetOpaque(child);
2643 : :
2792 teodor@sigaev.ru 2644 [ # # ]: 0 : if (P_ISLEAF(copaque))
2645 : 0 : break;
2646 : :
2647 : : /* Do an extra sanity check in passing on internal pages */
1756 pg@bowt.ie 2648 [ # # ]: 0 : if (copaque->btpo_level != level - 1)
2792 teodor@sigaev.ru 2649 [ # # ]: 0 : ereport(ERROR,
2650 : : (errcode(ERRCODE_INDEX_CORRUPTED),
2651 : : errmsg_internal("downlink points to block in index \"%s\" whose level is not one level down",
2652 : : RelationGetRelationName(state->rel)),
2653 : : errdetail_internal("Top parent/under check block=%u block pointed to=%u expected level=%u level in pointed to block=%u.",
2654 : : blkno, childblk,
2655 : : level - 1, copaque->btpo_level)));
2656 : :
1756 pg@bowt.ie 2657 : 0 : level = copaque->btpo_level;
2427 2658 : 0 : itemid = PageGetItemIdCareful(state, childblk, child,
2659 [ # # ]: 0 : P_FIRSTDATAKEY(copaque));
2792 teodor@sigaev.ru 2660 : 0 : itup = (IndexTuple) PageGetItem(child, itemid);
2192 pg@bowt.ie 2661 : 0 : childblk = BTreeTupleGetDownLink(itup);
2662 : : /* Be slightly more pro-active in freeing this memory, just in case */
2792 teodor@sigaev.ru 2663 : 0 : pfree(child);
2664 : : }
2665 : :
2666 : : /*
2667 : : * Since there cannot be a concurrent VACUUM operation in readonly mode,
2668 : : * and since a page has no links within other pages (siblings and parent)
2669 : : * once it is marked fully deleted, it should be impossible to land on a
2670 : : * fully deleted page. See bt_child_check() for further details.
2671 : : *
2672 : : * The bt_child_check() P_ISDELETED() check is repeated here because
2673 : : * bt_child_check() does not visit pages reachable through negative
2674 : : * infinity items. Besides, bt_child_check() is unwilling to descend
2675 : : * multiple levels. (The similar bt_child_check() P_ISDELETED() check
2676 : : * within bt_check_level_from_leftmost() won't reach the page either,
2677 : : * since the leaf's live siblings should have their sibling links updated
2678 : : * to bypass the deletion target page when it is marked fully dead.)
2679 : : *
2680 : : * If this error is raised, it might be due to a previous multi-level page
2681 : : * deletion that failed to realize that it wasn't yet safe to mark the
2682 : : * leaf page as fully dead. A "dangling downlink" will still remain when
2683 : : * this happens. The fact that the dangling downlink's page (the leaf's
2684 : : * parent/ancestor page) lacked a downlink is incidental.
2685 : : */
2686 [ # # ]: 0 : if (P_ISDELETED(copaque))
2687 [ # # ]: 0 : ereport(ERROR,
2688 : : (errcode(ERRCODE_INDEX_CORRUPTED),
2689 : : errmsg_internal("downlink to deleted leaf page found in index \"%s\"",
2690 : : RelationGetRelationName(state->rel)),
2691 : : errdetail_internal("Top parent/target block=%u leaf block=%u top parent/under check lsn=%X/%08X.",
2692 : : blkno, childblk,
2693 : : LSN_FORMAT_ARGS(pagelsn))));
2694 : :
2695 : : /*
2696 : : * Iff leaf page is half-dead, its high key top parent link should point
2697 : : * to what VACUUM considered to be the top parent page at the instant it
2698 : : * was interrupted. Provided the high key link actually points to the
2699 : : * page under check, the missing downlink we detected is consistent with
2700 : : * there having been an interrupted multi-level page deletion. This means
2701 : : * that the subtree with the page under check at its root (a page deletion
2702 : : * chain) is in a consistent state, enabling VACUUM to resume deleting the
2703 : : * entire chain the next time it encounters the half-dead leaf page.
2704 : : */
2705 [ # # # # ]: 0 : if (P_ISHALFDEAD(copaque) && !P_RIGHTMOST(copaque))
2706 : : {
2427 pg@bowt.ie 2707 : 0 : itemid = PageGetItemIdCareful(state, childblk, child, P_HIKEY);
2792 teodor@sigaev.ru 2708 : 0 : itup = (IndexTuple) PageGetItem(child, itemid);
2106 akorotkov@postgresql 2709 [ # # ]: 0 : if (BTreeTupleGetTopParent(itup) == blkno)
2792 teodor@sigaev.ru 2710 : 0 : return;
2711 : : }
2712 : :
2713 [ # # ]: 0 : ereport(ERROR,
2714 : : (errcode(ERRCODE_INDEX_CORRUPTED),
2715 : : errmsg("internal index block lacks downlink in index \"%s\"",
2716 : : RelationGetRelationName(state->rel)),
2717 : : errdetail_internal("Block=%u level=%u page lsn=%X/%08X.",
2718 : : blkno, opaque->btpo_level,
2719 : : LSN_FORMAT_ARGS(pagelsn))));
2720 : : }
2721 : :
2722 : : /*
2723 : : * Per-tuple callback from table_index_build_scan, used to determine if index has
2724 : : * all the entries that definitely should have been observed in leaf pages of
2725 : : * the target index (that is, all IndexTuples that were fingerprinted by our
2726 : : * Bloom filter). All heapallindexed checks occur here.
2727 : : *
2728 : : * The redundancy between an index and the table it indexes provides a good
2729 : : * opportunity to detect corruption, especially corruption within the table.
2730 : : * The high level principle behind the verification performed here is that any
2731 : : * IndexTuple that should be in an index following a fresh CREATE INDEX (based
2732 : : * on the same index definition) should also have been in the original,
2733 : : * existing index, which should have used exactly the same representation
2734 : : *
2735 : : * Since the overall structure of the index has already been verified, the most
2736 : : * likely explanation for error here is a corrupt heap page (could be logical
2737 : : * or physical corruption). Index corruption may still be detected here,
2738 : : * though. Only readonly callers will have verified that left links and right
2739 : : * links are in agreement, and so it's possible that a leaf page transposition
2740 : : * within index is actually the source of corruption detected here (for
2741 : : * !readonly callers). The checks performed only for readonly callers might
2742 : : * more accurately frame the problem as a cross-page invariant issue (this
2743 : : * could even be due to recovery not replaying all WAL records). The !readonly
2744 : : * ERROR message raised here includes a HINT about retrying with readonly
2745 : : * verification, just in case it's a cross-page invariant issue, though that
2746 : : * isn't particularly likely.
2747 : : *
2748 : : * table_index_build_scan() expects to be able to find the root tuple when a
2749 : : * heap-only tuple (the live tuple at the end of some HOT chain) needs to be
2750 : : * indexed, in order to replace the actual tuple's TID with the root tuple's
2751 : : * TID (which is what we're actually passed back here). The index build heap
2752 : : * scan code will raise an error when a tuple that claims to be the root of the
2753 : : * heap-only tuple's HOT chain cannot be located. This catches cases where the
2754 : : * original root item offset/root tuple for a HOT chain indicates (for whatever
2755 : : * reason) that the entire HOT chain is dead, despite the fact that the latest
2756 : : * heap-only tuple should be indexed. When this happens, sequential scans may
2757 : : * always give correct answers, and all indexes may be considered structurally
2758 : : * consistent (i.e. the nbtree structural checks would not detect corruption).
2759 : : * It may be the case that only index scans give wrong answers, and yet heap or
2760 : : * SLRU corruption is the real culprit. (While it's true that LP_DEAD bit
2761 : : * setting will probably also leave the index in a corrupt state before too
2762 : : * long, the problem is nonetheless that there is heap corruption.)
2763 : : *
2764 : : * Heap-only tuple handling within table_index_build_scan() works in a way that
2765 : : * helps us to detect index tuples that contain the wrong values (values that
2766 : : * don't match the latest tuple in the HOT chain). This can happen when there
2767 : : * is no superseding index tuple due to a faulty assessment of HOT safety,
2768 : : * perhaps during the original CREATE INDEX. Because the latest tuple's
2769 : : * contents are used with the root TID, an error will be raised when a tuple
2770 : : * with the same TID but non-matching attribute values is passed back to us.
2771 : : * Faulty assessment of HOT-safety was behind at least two distinct CREATE
2772 : : * INDEX CONCURRENTLY bugs that made it into stable releases, one of which was
2773 : : * undetected for many years. In short, the same principle that allows a
2774 : : * REINDEX to repair corruption when there was an (undetected) broken HOT chain
2775 : : * also allows us to detect the corruption in many cases.
2776 : : */
2777 : : static void
2230 andres@anarazel.de 2778 :CBC 531868 : bt_tuple_present_callback(Relation index, ItemPointer tid, Datum *values,
2779 : : bool *isnull, bool tupleIsAlive, void *checkstate)
2780 : : {
2817 2781 : 531868 : BtreeCheckState *state = (BtreeCheckState *) checkstate;
2782 : : IndexTuple itup,
2783 : : norm;
2784 : :
2785 [ - + ]: 531868 : Assert(state->heapallindexed);
2786 : :
2787 : : /* Generate a normalized index tuple for fingerprinting */
2788 : 531868 : itup = index_form_tuple(RelationGetDescr(index), values, isnull);
2230 2789 : 531868 : itup->t_tid = *tid;
2505 pg@bowt.ie 2790 : 531868 : norm = bt_normalize_tuple(state, itup);
2791 : :
2792 : : /* Probe Bloom filter -- tuple should be present */
2793 [ - + ]: 531868 : if (bloom_lacks_element(state->filter, (unsigned char *) norm,
2794 : : IndexTupleSize(norm)))
2817 andres@anarazel.de 2795 [ # # # # ]:UBC 0 : ereport(ERROR,
2796 : : (errcode(ERRCODE_DATA_CORRUPTED),
2797 : : errmsg("heap tuple (%u,%u) from table \"%s\" lacks matching index tuple within index \"%s\"",
2798 : : ItemPointerGetBlockNumber(&(itup->t_tid)),
2799 : : ItemPointerGetOffsetNumber(&(itup->t_tid)),
2800 : : RelationGetRelationName(state->heaprel),
2801 : : RelationGetRelationName(state->rel)),
2802 : : !state->readonly
2803 : : ? errhint("Retrying verification using the function bt_index_parent_check() might provide a more specific error.")
2804 : : : 0));
2805 : :
2817 andres@anarazel.de 2806 :CBC 531868 : state->heaptuplespresent++;
2807 : 531868 : pfree(itup);
2808 : : /* Cannot leak memory here */
2505 pg@bowt.ie 2809 [ + + ]: 531868 : if (norm != itup)
2810 : 5 : pfree(norm);
2811 : 531868 : }
2812 : :
2813 : : /*
2814 : : * Normalize an index tuple for fingerprinting.
2815 : : *
2816 : : * In general, index tuple formation is assumed to be deterministic by
2817 : : * heapallindexed verification, and IndexTuples are assumed immutable. While
2818 : : * the LP_DEAD bit is mutable in leaf pages, that's ItemId metadata, which is
2819 : : * not fingerprinted. Normalization is required to compensate for corner
2820 : : * cases where the determinism assumption doesn't quite work.
2821 : : *
2822 : : * There is currently one such case: index_form_tuple() does not try to hide
2823 : : * the source TOAST state of input datums. The executor applies TOAST
2824 : : * compression for heap tuples based on different criteria to the compression
2825 : : * applied within btinsert()'s call to index_form_tuple(): it sometimes
2826 : : * compresses more aggressively, resulting in compressed heap tuple datums but
2827 : : * uncompressed corresponding index tuple datums. A subsequent heapallindexed
2828 : : * verification will get a logically equivalent though bitwise unequal tuple
2829 : : * from index_form_tuple(). False positive heapallindexed corruption reports
2830 : : * could occur without normalizing away the inconsistency.
2831 : : *
2832 : : * Returned tuple is often caller's own original tuple. Otherwise, it is a
2833 : : * new representation of caller's original index tuple, palloc()'d in caller's
2834 : : * memory context.
2835 : : *
2836 : : * Note: This routine is not concerned with distinctions about the
2837 : : * representation of tuples beyond those that might break heapallindexed
2838 : : * verification. In particular, it won't try to normalize opclass-equal
2839 : : * datums with potentially distinct representations (e.g., btree/numeric_ops
2840 : : * index datums will not get their display scale normalized-away here).
2841 : : * Caller does normalization for non-pivot tuples that have a posting list,
2842 : : * since dummy CREATE INDEX callback code generates new tuples with the same
2843 : : * normalized representation.
2844 : : */
2845 : : static IndexTuple
2846 : 1066133 : bt_normalize_tuple(BtreeCheckState *state, IndexTuple itup)
2847 : : {
2848 : 1066133 : TupleDesc tupleDescriptor = RelationGetDescr(state->rel);
2849 : : Datum normalized[INDEX_MAX_KEYS];
2850 : : bool isnull[INDEX_MAX_KEYS];
2851 : : bool need_free[INDEX_MAX_KEYS];
2852 : 1066133 : bool formnewtup = false;
2853 : : IndexTuple reformed;
2854 : : int i;
2855 : :
2856 : : /* Caller should only pass "logical" non-pivot tuples here */
2120 2857 [ + - - + ]: 1066133 : Assert(!BTreeTupleIsPosting(itup) && !BTreeTupleIsPivot(itup));
2858 : :
2859 : : /* Easy case: It's immediately clear that tuple has no varlena datums */
2505 2860 [ + + ]: 1066133 : if (!IndexTupleHasVarwidths(itup))
2861 : 1066109 : return itup;
2862 : :
2863 [ + + ]: 48 : for (i = 0; i < tupleDescriptor->natts; i++)
2864 : : {
2865 : : Form_pg_attribute att;
2866 : :
2867 : 24 : att = TupleDescAttr(tupleDescriptor, i);
2868 : :
2869 : : /* Assume untoasted/already normalized datum initially */
633 akorotkov@postgresql 2870 : 24 : need_free[i] = false;
2505 pg@bowt.ie 2871 : 24 : normalized[i] = index_getattr(itup, att->attnum,
2872 : : tupleDescriptor,
2873 : : &isnull[i]);
2874 [ + - + - : 24 : if (att->attbyval || att->attlen != -1 || isnull[i])
- + ]
2505 pg@bowt.ie 2875 :UBC 0 : continue;
2876 : :
2877 : : /*
2878 : : * Callers always pass a tuple that could safely be inserted into the
2879 : : * index without further processing, so an external varlena header
2880 : : * should never be encountered here
2881 : : */
2505 pg@bowt.ie 2882 [ - + ]:CBC 24 : if (VARATT_IS_EXTERNAL(DatumGetPointer(normalized[i])))
2505 pg@bowt.ie 2883 [ # # ]:UBC 0 : ereport(ERROR,
2884 : : (errcode(ERRCODE_INDEX_CORRUPTED),
2885 : : errmsg("external varlena datum in tuple that references heap row (%u,%u) in index \"%s\"",
2886 : : ItemPointerGetBlockNumber(&(itup->t_tid)),
2887 : : ItemPointerGetOffsetNumber(&(itup->t_tid)),
2888 : : RelationGetRelationName(state->rel))));
633 akorotkov@postgresql 2889 [ + + + + ]:CBC 46 : else if (!VARATT_IS_COMPRESSED(DatumGetPointer(normalized[i])) &&
2890 [ + + ]: 22 : VARSIZE(DatumGetPointer(normalized[i])) > TOAST_INDEX_TARGET &&
2891 [ + + ]: 21 : (att->attstorage == TYPSTORAGE_EXTENDED ||
2892 [ - + ]: 16 : att->attstorage == TYPSTORAGE_MAIN))
2893 : : {
2894 : : /*
2895 : : * This value will be compressed by index_form_tuple() with the
2896 : : * current storage settings. We may be here because this tuple
2897 : : * was formed with different storage settings. So, force forming.
2898 : : */
2899 : 5 : formnewtup = true;
2900 : : }
2505 pg@bowt.ie 2901 [ + + ]: 19 : else if (VARATT_IS_COMPRESSED(DatumGetPointer(normalized[i])))
2902 : : {
2903 : 2 : formnewtup = true;
2904 : 2 : normalized[i] = PointerGetDatum(PG_DETOAST_DATUM(normalized[i]));
633 akorotkov@postgresql 2905 : 2 : need_free[i] = true;
2906 : : }
2907 : :
2908 : : /*
2909 : : * Short tuples may have 1B or 4B header. Convert 4B header of short
2910 : : * tuples to 1B
2911 : : */
2912 [ + + + + ]: 17 : else if (VARATT_CAN_MAKE_SHORT(DatumGetPointer(normalized[i])))
2913 : : {
2914 : : /* convert to short varlena */
2915 : 1 : Size len = VARATT_CONVERTED_SHORT_SIZE(DatumGetPointer(normalized[i]));
2916 : 1 : char *data = palloc(len);
2917 : :
2918 : 1 : SET_VARSIZE_SHORT(data, len);
2919 : 1 : memcpy(data + 1, VARDATA(DatumGetPointer(normalized[i])), len - 1);
2920 : :
2921 : 1 : formnewtup = true;
2922 : 1 : normalized[i] = PointerGetDatum(data);
2923 : 1 : need_free[i] = true;
2924 : : }
2925 : : }
2926 : :
2927 : : /*
2928 : : * Easier case: Tuple has varlena datums, none of which are compressed or
2929 : : * short with 4B header
2930 : : */
2505 pg@bowt.ie 2931 [ + + ]: 24 : if (!formnewtup)
2932 : 16 : return itup;
2933 : :
2934 : : /*
2935 : : * Hard case: Tuple had compressed varlena datums that necessitate
2936 : : * creating normalized version of the tuple from uncompressed input datums
2937 : : * (normalized input datums). This is rather naive, but shouldn't be
2938 : : * necessary too often.
2939 : : *
2940 : : * In the heap, tuples may contain short varlena datums with both 1B
2941 : : * header and 4B headers. But the corresponding index tuple should always
2942 : : * have such varlena's with 1B headers. So, if there is a short varlena
2943 : : * with 4B header, we need to convert it for fingerprinting.
2944 : : *
2945 : : * Note that we rely on deterministic index_form_tuple() TOAST compression
2946 : : * of normalized input.
2947 : : */
2948 : 8 : reformed = index_form_tuple(tupleDescriptor, normalized, isnull);
2949 : 8 : reformed->t_tid = itup->t_tid;
2950 : :
2951 : : /* Cannot leak memory here */
2952 [ + + ]: 16 : for (i = 0; i < tupleDescriptor->natts; i++)
633 akorotkov@postgresql 2953 [ + + ]: 8 : if (need_free[i])
2505 pg@bowt.ie 2954 : 3 : pfree(DatumGetPointer(normalized[i]));
2955 : :
2956 : 8 : return reformed;
2957 : : }
2958 : :
2959 : : /*
2960 : : * Produce palloc()'d "plain" tuple for nth posting list entry/TID.
2961 : : *
2962 : : * In general, deduplication is not supposed to change the logical contents of
2963 : : * an index. Multiple index tuples are merged together into one equivalent
2964 : : * posting list index tuple when convenient.
2965 : : *
2966 : : * heapallindexed verification must normalize-away this variation in
2967 : : * representation by converting posting list tuples into two or more "plain"
2968 : : * tuples. Each tuple must be fingerprinted separately -- there must be one
2969 : : * tuple for each corresponding Bloom filter probe during the heap scan.
2970 : : *
2971 : : * Note: Caller still needs to call bt_normalize_tuple() with returned tuple.
2972 : : */
2973 : : static inline IndexTuple
2120 2974 : 27449 : bt_posting_plain_tuple(IndexTuple itup, int n)
2975 : : {
2976 [ - + ]: 27449 : Assert(BTreeTupleIsPosting(itup));
2977 : :
2978 : : /* Returns non-posting-list tuple */
2979 : 27449 : return _bt_form_posting(itup, BTreeTupleGetPostingN(itup, n), 1);
2980 : : }
2981 : :
2982 : : /*
2983 : : * Search for itup in index, starting from fast root page. itup must be a
2984 : : * non-pivot tuple. This is only supported with heapkeyspace indexes, since
2985 : : * we rely on having fully unique keys to find a match with only a single
2986 : : * visit to a leaf page, barring an interrupted page split, where we may have
2987 : : * to move right. (A concurrent page split is impossible because caller must
2988 : : * be readonly caller.)
2989 : : *
2990 : : * This routine can detect very subtle transitive consistency issues across
2991 : : * more than one level of the tree. Leaf pages all have a high key (even the
2992 : : * rightmost page has a conceptual positive infinity high key), but not a low
2993 : : * key. Their downlink in parent is a lower bound, which along with the high
2994 : : * key is almost enough to detect every possible inconsistency. A downlink
2995 : : * separator key value won't always be available from parent, though, because
2996 : : * the first items of internal pages are negative infinity items, truncated
2997 : : * down to zero attributes during internal page splits. While it's true that
2998 : : * bt_child_check() and the high key check can detect most imaginable key
2999 : : * space problems, there are remaining problems it won't detect with non-pivot
3000 : : * tuples in cousin leaf pages. Starting a search from the root for every
3001 : : * existing leaf tuple detects small inconsistencies in upper levels of the
3002 : : * tree that cannot be detected any other way. (Besides all this, this is
3003 : : * probably also useful as a direct test of the code used by index scans
3004 : : * themselves.)
3005 : : */
3006 : : static bool
2463 3007 : 201098 : bt_rootdescend(BtreeCheckState *state, IndexTuple itup)
3008 : : {
3009 : : BTScanInsert key;
3010 : : BTStack stack;
3011 : : Buffer lbuf;
3012 : : bool exists;
3013 : :
920 3014 : 201098 : key = _bt_mkscankey(state->rel, itup);
2463 3015 [ + - - + ]: 201098 : Assert(key->heapkeyspace && key->scantid != NULL);
3016 : :
3017 : : /*
3018 : : * Search from root.
3019 : : *
3020 : : * Ideally, we would arrange to only move right within _bt_search() when
3021 : : * an interrupted page split is detected (i.e. when the incomplete split
3022 : : * bit is found to be set), but for now we accept the possibility that
3023 : : * that could conceal an inconsistency.
3024 : : */
3025 [ + - - + ]: 201098 : Assert(state->readonly && state->rootdescend);
3026 : 201098 : exists = false;
830 tmunro@postgresql.or 3027 : 201098 : stack = _bt_search(state->rel, NULL, key, &lbuf, BT_READ);
3028 : :
2463 pg@bowt.ie 3029 [ + - ]: 201098 : if (BufferIsValid(lbuf))
3030 : : {
3031 : : BTInsertStateData insertstate;
3032 : : OffsetNumber offnum;
3033 : : Page page;
3034 : :
3035 : 201098 : insertstate.itup = itup;
3036 : 201098 : insertstate.itemsz = MAXALIGN(IndexTupleSize(itup));
3037 : 201098 : insertstate.itup_key = key;
2120 3038 : 201098 : insertstate.postingoff = 0;
2463 3039 : 201098 : insertstate.bounds_valid = false;
3040 : 201098 : insertstate.buf = lbuf;
3041 : :
3042 : : /* Get matching tuple on leaf page */
3043 : 201098 : offnum = _bt_binsrch_insert(state->rel, &insertstate);
3044 : : /* Compare first >= matching item on leaf page, if any */
3045 : 201098 : page = BufferGetPage(lbuf);
3046 : : /* Should match on first heap TID when tuple has a posting list */
3047 [ + - ]: 201098 : if (offnum <= PageGetMaxOffsetNumber(page) &&
2120 3048 [ + - + - ]: 402196 : insertstate.postingoff <= 0 &&
2463 3049 : 201098 : _bt_compare(state->rel, key, page, offnum) == 0)
3050 : 201098 : exists = true;
3051 : 201098 : _bt_relbuf(state->rel, lbuf);
3052 : : }
3053 : :
3054 : 201098 : _bt_freestack(stack);
3055 : 201098 : pfree(key);
3056 : :
3057 : 201098 : return exists;
3058 : : }
3059 : :
3060 : : /*
3061 : : * Is particular offset within page (whose special state is passed by caller)
3062 : : * the page negative-infinity item?
3063 : : *
3064 : : * As noted in comments above _bt_compare(), there is special handling of the
3065 : : * first data item as a "negative infinity" item. The hard-coding within
3066 : : * _bt_compare() makes comparing this item for the purposes of verification
3067 : : * pointless at best, since the IndexTuple only contains a valid TID (a
3068 : : * reference TID to child page).
3069 : : */
3070 : : static inline bool
3204 andres@anarazel.de 3071 : 2655508 : offset_is_negative_infinity(BTPageOpaque opaque, OffsetNumber offset)
3072 : : {
3073 : : /*
3074 : : * For internal pages only, the first item after high key, if any, is
3075 : : * negative infinity item. Internal pages always have a negative infinity
3076 : : * item, whereas leaf pages never have one. This implies that negative
3077 : : * infinity item is either first or second line item, or there is none
3078 : : * within page.
3079 : : *
3080 : : * Negative infinity items are a special case among pivot tuples. They
3081 : : * always have zero attributes, while all other pivot tuples always have
3082 : : * nkeyatts attributes.
3083 : : *
3084 : : * Right-most pages don't have a high key, but could be said to
3085 : : * conceptually have a "positive infinity" high key. Thus, there is a
3086 : : * symmetry between down link items in parent pages, and high keys in
3087 : : * children. Together, they represent the part of the key space that
3088 : : * belongs to each page in the index. For example, all children of the
3089 : : * root page will have negative infinity as a lower bound from root
3090 : : * negative infinity downlink, and positive infinity as an upper bound
3091 : : * (implicitly, from "imaginary" positive infinity high key in root).
3092 : : */
3093 [ + + + + : 2655508 : return !P_ISLEAF(opaque) && offset == P_FIRSTDATAKEY(opaque);
+ + ]
3094 : : }
3095 : :
3096 : : /*
3097 : : * Does the invariant hold that the key is strictly less than a given upper
3098 : : * bound offset item?
3099 : : *
3100 : : * Verifies line pointer on behalf of caller.
3101 : : *
3102 : : * If this function returns false, convention is that caller throws error due
3103 : : * to corruption.
3104 : : */
3105 : : static inline bool
2463 pg@bowt.ie 3106 : 2045870 : invariant_l_offset(BtreeCheckState *state, BTScanInsert key,
3107 : : OffsetNumber upperbound)
3108 : : {
3109 : : ItemId itemid;
3110 : : int32 cmp;
3111 : :
739 3112 [ + - - + ]: 2045870 : Assert(!key->nextkey && key->backward);
3113 : :
3114 : : /* Verify line pointer before checking tuple */
2427 3115 : 2045870 : itemid = PageGetItemIdCareful(state, state->targetblock, state->target,
3116 : : upperbound);
3117 : : /* pg_upgrade'd indexes may legally have equal sibling tuples */
2463 3118 [ - + ]: 2045870 : if (!key->heapkeyspace)
2463 pg@bowt.ie 3119 :UBC 0 : return invariant_leq_offset(state, key, upperbound);
3120 : :
2463 pg@bowt.ie 3121 :CBC 2045870 : cmp = _bt_compare(state->rel, key, state->target, upperbound);
3122 : :
3123 : : /*
3124 : : * _bt_compare() is capable of determining that a scankey with a
3125 : : * filled-out attribute is greater than pivot tuples where the comparison
3126 : : * is resolved at a truncated attribute (value of attribute in pivot is
3127 : : * minus infinity). However, it is not capable of determining that a
3128 : : * scankey is _less than_ a tuple on the basis of a comparison resolved at
3129 : : * _scankey_ minus infinity attribute. Complete an extra step to simulate
3130 : : * having minus infinity values for omitted scankey attribute(s).
3131 : : */
3132 [ - + ]: 2045870 : if (cmp == 0)
3133 : : {
3134 : : BTPageOpaque topaque;
3135 : : IndexTuple ritup;
3136 : : int uppnkeyatts;
3137 : : ItemPointer rheaptid;
3138 : : bool nonpivot;
3139 : :
2463 pg@bowt.ie 3140 :UBC 0 : ritup = (IndexTuple) PageGetItem(state->target, itemid);
1355 michael@paquier.xyz 3141 : 0 : topaque = BTPageGetOpaque(state->target);
2463 pg@bowt.ie 3142 [ # # # # : 0 : nonpivot = P_ISLEAF(topaque) && upperbound >= P_FIRSTDATAKEY(topaque);
# # ]
3143 : :
3144 : : /* Get number of keys + heap TID for item to the right */
3145 [ # # # # : 0 : uppnkeyatts = BTreeTupleGetNKeyAtts(ritup, state->rel);
# # ]
3146 : 0 : rheaptid = BTreeTupleGetHeapTIDCareful(state, ritup, nonpivot);
3147 : :
3148 : : /* Heap TID is tiebreaker key attribute */
3149 [ # # ]: 0 : if (key->keysz == uppnkeyatts)
3150 [ # # # # ]: 0 : return key->scantid == NULL && rheaptid != NULL;
3151 : :
3152 : 0 : return key->keysz < uppnkeyatts;
3153 : : }
3154 : :
2463 pg@bowt.ie 3155 :CBC 2045870 : return cmp < 0;
3156 : : }
3157 : :
3158 : : /*
3159 : : * Does the invariant hold that the key is less than or equal to a given upper
3160 : : * bound offset item?
3161 : : *
3162 : : * Caller should have verified that upperbound's line pointer is consistent
3163 : : * using PageGetItemIdCareful() call.
3164 : : *
3165 : : * If this function returns false, convention is that caller throws error due
3166 : : * to corruption.
3167 : : */
3168 : : static inline bool
3169 : 1882515 : invariant_leq_offset(BtreeCheckState *state, BTScanInsert key,
3170 : : OffsetNumber upperbound)
3171 : : {
3172 : : int32 cmp;
3173 : :
739 3174 [ + - - + ]: 1882515 : Assert(!key->nextkey && key->backward);
3175 : :
2463 3176 : 1882515 : cmp = _bt_compare(state->rel, key, state->target, upperbound);
3177 : :
3204 andres@anarazel.de 3178 : 1882515 : return cmp <= 0;
3179 : : }
3180 : :
3181 : : /*
3182 : : * Does the invariant hold that the key is strictly greater than a given lower
3183 : : * bound offset item?
3184 : : *
3185 : : * Caller should have verified that lowerbound's line pointer is consistent
3186 : : * using PageGetItemIdCareful() call.
3187 : : *
3188 : : * If this function returns false, convention is that caller throws error due
3189 : : * to corruption.
3190 : : */
3191 : : static inline bool
2463 pg@bowt.ie 3192 : 6803 : invariant_g_offset(BtreeCheckState *state, BTScanInsert key,
3193 : : OffsetNumber lowerbound)
3194 : : {
3195 : : int32 cmp;
3196 : :
739 3197 [ + - - + ]: 6803 : Assert(!key->nextkey && key->backward);
3198 : :
2463 3199 : 6803 : cmp = _bt_compare(state->rel, key, state->target, lowerbound);
3200 : :
3201 : : /* pg_upgrade'd indexes may legally have equal sibling tuples */
3202 [ - + ]: 6803 : if (!key->heapkeyspace)
2463 pg@bowt.ie 3203 :UBC 0 : return cmp >= 0;
3204 : :
3205 : : /*
3206 : : * No need to consider the possibility that scankey has attributes that we
3207 : : * need to force to be interpreted as negative infinity. _bt_compare() is
3208 : : * able to determine that scankey is greater than negative infinity. The
3209 : : * distinction between "==" and "<" isn't interesting here, since
3210 : : * corruption is indicated either way.
3211 : : */
2463 pg@bowt.ie 3212 :CBC 6803 : return cmp > 0;
3213 : : }
3214 : :
3215 : : /*
3216 : : * Does the invariant hold that the key is strictly less than a given upper
3217 : : * bound offset item, with the offset relating to a caller-supplied page that
3218 : : * is not the current target page?
3219 : : *
3220 : : * Caller's non-target page is a child page of the target, checked as part of
3221 : : * checking a property of the target page (i.e. the key comes from the
3222 : : * target). Verifies line pointer on behalf of caller.
3223 : : *
3224 : : * If this function returns false, convention is that caller throws error due
3225 : : * to corruption.
3226 : : */
3227 : : static inline bool
3228 : 598488 : invariant_l_nontarget_offset(BtreeCheckState *state, BTScanInsert key,
3229 : : BlockNumber nontargetblock, Page nontarget,
3230 : : OffsetNumber upperbound)
3231 : : {
3232 : : ItemId itemid;
3233 : : int32 cmp;
3234 : :
739 3235 [ + - - + ]: 598488 : Assert(!key->nextkey && key->backward);
3236 : :
3237 : : /* Verify line pointer before checking tuple */
2427 3238 : 598488 : itemid = PageGetItemIdCareful(state, nontargetblock, nontarget,
3239 : : upperbound);
2463 3240 : 598488 : cmp = _bt_compare(state->rel, key, nontarget, upperbound);
3241 : :
3242 : : /* pg_upgrade'd indexes may legally have equal sibling tuples */
3243 [ - + ]: 598488 : if (!key->heapkeyspace)
2463 pg@bowt.ie 3244 :UBC 0 : return cmp <= 0;
3245 : :
3246 : : /* See invariant_l_offset() for an explanation of this extra step */
2463 pg@bowt.ie 3247 [ + + ]:CBC 598488 : if (cmp == 0)
3248 : : {
3249 : : IndexTuple child;
3250 : : int uppnkeyatts;
3251 : : ItemPointer childheaptid;
3252 : : BTPageOpaque copaque;
3253 : : bool nonpivot;
3254 : :
3255 : 1860 : child = (IndexTuple) PageGetItem(nontarget, itemid);
1355 michael@paquier.xyz 3256 : 1860 : copaque = BTPageGetOpaque(nontarget);
2463 pg@bowt.ie 3257 [ + - + + : 1860 : nonpivot = P_ISLEAF(copaque) && upperbound >= P_FIRSTDATAKEY(copaque);
+ - ]
3258 : :
3259 : : /* Get number of keys + heap TID for child/non-target item */
3260 [ - + + + : 1860 : uppnkeyatts = BTreeTupleGetNKeyAtts(child, state->rel);
- + ]
3261 : 1860 : childheaptid = BTreeTupleGetHeapTIDCareful(state, child, nonpivot);
3262 : :
3263 : : /* Heap TID is tiebreaker key attribute */
3264 [ + - ]: 1860 : if (key->keysz == uppnkeyatts)
3265 [ + - + - ]: 1860 : return key->scantid == NULL && childheaptid != NULL;
3266 : :
2463 pg@bowt.ie 3267 :UBC 0 : return key->keysz < uppnkeyatts;
3268 : : }
3269 : :
2463 pg@bowt.ie 3270 :CBC 596628 : return cmp < 0;
3271 : : }
3272 : :
3273 : : /*
3274 : : * Given a block number of a B-Tree page, return page in palloc()'d memory.
3275 : : * While at it, perform some basic checks of the page.
3276 : : *
3277 : : * There is never an attempt to get a consistent view of multiple pages using
3278 : : * multiple concurrent buffer locks; in general, we only acquire a single pin
3279 : : * and buffer lock at a time, which is often all that the nbtree code requires.
3280 : : * (Actually, bt_recheck_sibling_links couples buffer locks, which is the only
3281 : : * exception to this general rule.)
3282 : : *
3283 : : * Operating on a copy of the page is useful because it prevents control
3284 : : * getting stuck in an uninterruptible state when an underlying operator class
3285 : : * misbehaves.
3286 : : */
3287 : : static Page
3204 andres@anarazel.de 3288 : 21972 : palloc_btree_page(BtreeCheckState *state, BlockNumber blocknum)
3289 : : {
3290 : : Buffer buffer;
3291 : : Page page;
3292 : : BTPageOpaque opaque;
3293 : : OffsetNumber maxoffset;
3294 : :
3295 : 21972 : page = palloc(BLCKSZ);
3296 : :
3297 : : /*
3298 : : * We copy the page into local storage to avoid holding pin on the buffer
3299 : : * longer than we must.
3300 : : */
3301 : 21972 : buffer = ReadBufferExtended(state->rel, MAIN_FORKNUM, blocknum, RBM_NORMAL,
3302 : : state->checkstrategy);
3303 : 21960 : LockBuffer(buffer, BT_READ);
3304 : :
3305 : : /*
3306 : : * Perform the same basic sanity checking that nbtree itself performs for
3307 : : * every page:
3308 : : */
3309 : 21960 : _bt_checkpage(state->rel, buffer);
3310 : :
3311 : : /* Only use copy of page in palloc()'d memory */
3312 : 21960 : memcpy(page, BufferGetPage(buffer), BLCKSZ);
3313 : 21960 : UnlockReleaseBuffer(buffer);
3314 : :
1355 michael@paquier.xyz 3315 : 21960 : opaque = BTPageGetOpaque(page);
3316 : :
3011 tgl@sss.pgh.pa.us 3317 [ + + - + ]: 21960 : if (P_ISMETA(opaque) && blocknum != BTREE_METAPAGE)
3204 andres@anarazel.de 3318 [ # # ]:UBC 0 : ereport(ERROR,
3319 : : (errcode(ERRCODE_INDEX_CORRUPTED),
3320 : : errmsg("invalid meta page found at block %u in index \"%s\"",
3321 : : blocknum, RelationGetRelationName(state->rel))));
3322 : :
3323 : : /* Check page from block that ought to be meta page */
3204 andres@anarazel.de 3324 [ + + ]:CBC 21960 : if (blocknum == BTREE_METAPAGE)
3325 : : {
3326 : 3978 : BTMetaPageData *metad = BTPageGetMeta(page);
3327 : :
3011 tgl@sss.pgh.pa.us 3328 [ + - ]: 3978 : if (!P_ISMETA(opaque) ||
3204 andres@anarazel.de 3329 [ - + ]: 3978 : metad->btm_magic != BTREE_MAGIC)
3204 andres@anarazel.de 3330 [ # # ]:UBC 0 : ereport(ERROR,
3331 : : (errcode(ERRCODE_INDEX_CORRUPTED),
3332 : : errmsg("index \"%s\" meta page is corrupt",
3333 : : RelationGetRelationName(state->rel))));
3334 : :
2813 teodor@sigaev.ru 3335 [ + - ]:CBC 3978 : if (metad->btm_version < BTREE_MIN_VERSION ||
3336 [ - + ]: 3978 : metad->btm_version > BTREE_VERSION)
3204 andres@anarazel.de 3337 [ # # ]:UBC 0 : ereport(ERROR,
3338 : : (errcode(ERRCODE_INDEX_CORRUPTED),
3339 : : errmsg("version mismatch in index \"%s\": file version %d, "
3340 : : "current version %d, minimum supported version %d",
3341 : : RelationGetRelationName(state->rel),
3342 : : metad->btm_version, BTREE_VERSION,
3343 : : BTREE_MIN_VERSION)));
3344 : :
3345 : : /* Finished with metapage checks */
2792 teodor@sigaev.ru 3346 :CBC 3978 : return page;
3347 : : }
3348 : :
3349 : : /*
3350 : : * Deleted pages that still use the old 32-bit XID representation have no
3351 : : * sane "level" field because they type pun the field, but all other pages
3352 : : * (including pages deleted on Postgres 14+) have a valid value.
3353 : : */
1756 pg@bowt.ie 3354 [ - + - - ]: 17982 : if (!P_ISDELETED(opaque) || P_HAS_FULLXID(opaque))
3355 : : {
3356 : : /* Okay, no reason not to trust btpo_level field from page */
3357 : :
3358 [ + + - + ]: 17982 : if (P_ISLEAF(opaque) && opaque->btpo_level != 0)
1756 pg@bowt.ie 3359 [ # # ]:UBC 0 : ereport(ERROR,
3360 : : (errcode(ERRCODE_INDEX_CORRUPTED),
3361 : : errmsg_internal("invalid leaf page level %u for block %u in index \"%s\"",
3362 : : opaque->btpo_level, blocknum,
3363 : : RelationGetRelationName(state->rel))));
3364 : :
1756 pg@bowt.ie 3365 [ + + - + ]:CBC 17982 : if (!P_ISLEAF(opaque) && opaque->btpo_level == 0)
1756 pg@bowt.ie 3366 [ # # ]:UBC 0 : ereport(ERROR,
3367 : : (errcode(ERRCODE_INDEX_CORRUPTED),
3368 : : errmsg_internal("invalid internal page level 0 for block %u in index \"%s\"",
3369 : : blocknum,
3370 : : RelationGetRelationName(state->rel))));
3371 : : }
3372 : :
3373 : : /*
3374 : : * Sanity checks for number of items on page.
3375 : : *
3376 : : * As noted at the beginning of _bt_binsrch(), an internal page must have
3377 : : * children, since there must always be a negative infinity downlink
3378 : : * (there may also be a highkey). In the case of non-rightmost leaf
3379 : : * pages, there must be at least a highkey. The exceptions are deleted
3380 : : * pages, which contain no items.
3381 : : *
3382 : : * This is correct when pages are half-dead, since internal pages are
3383 : : * never half-dead, and leaf pages must have a high key when half-dead
3384 : : * (the rightmost page can never be deleted). It's also correct with
3385 : : * fully deleted pages: _bt_unlink_halfdead_page() doesn't change anything
3386 : : * about the target page other than setting the page as fully dead, and
3387 : : * setting its xact field. In particular, it doesn't change the sibling
3388 : : * links in the deletion target itself, since they're required when index
3389 : : * scans land on the deletion target, and then need to move right (or need
3390 : : * to move left, in the case of backward index scans).
3391 : : */
2792 teodor@sigaev.ru 3392 :CBC 17982 : maxoffset = PageGetMaxOffsetNumber(page);
3393 [ - + ]: 17982 : if (maxoffset > MaxIndexTuplesPerPage)
2792 teodor@sigaev.ru 3394 [ # # ]:UBC 0 : ereport(ERROR,
3395 : : (errcode(ERRCODE_INDEX_CORRUPTED),
3396 : : errmsg("Number of items on block %u of index \"%s\" exceeds MaxIndexTuplesPerPage (%u)",
3397 : : blocknum, RelationGetRelationName(state->rel),
3398 : : MaxIndexTuplesPerPage)));
3399 : :
2042 akorotkov@postgresql 3400 [ + + + - :CBC 17982 : if (!P_ISLEAF(opaque) && !P_ISDELETED(opaque) && maxoffset < P_FIRSTDATAKEY(opaque))
+ + - + ]
2792 teodor@sigaev.ru 3401 [ # # ]:UBC 0 : ereport(ERROR,
3402 : : (errcode(ERRCODE_INDEX_CORRUPTED),
3403 : : errmsg("internal block %u in index \"%s\" lacks high key and/or at least one downlink",
3404 : : blocknum, RelationGetRelationName(state->rel))));
3405 : :
2042 akorotkov@postgresql 3406 [ + + + - :CBC 17982 : if (P_ISLEAF(opaque) && !P_ISDELETED(opaque) && !P_RIGHTMOST(opaque) && maxoffset < P_HIKEY)
+ + - + ]
2792 teodor@sigaev.ru 3407 [ # # ]:UBC 0 : ereport(ERROR,
3408 : : (errcode(ERRCODE_INDEX_CORRUPTED),
3409 : : errmsg("non-rightmost leaf block %u in index \"%s\" lacks high key item",
3410 : : blocknum, RelationGetRelationName(state->rel))));
3411 : :
3412 : : /*
3413 : : * In general, internal pages are never marked half-dead, except on
3414 : : * versions of Postgres prior to 9.4, where it can be valid transient
3415 : : * state. This state is nonetheless treated as corruption by VACUUM on
3416 : : * from version 9.4 on, so do the same here. See _bt_pagedel() for full
3417 : : * details.
3418 : : */
2792 teodor@sigaev.ru 3419 [ + + - + ]:CBC 17982 : if (!P_ISLEAF(opaque) && P_ISHALFDEAD(opaque))
2792 teodor@sigaev.ru 3420 [ # # ]:UBC 0 : ereport(ERROR,
3421 : : (errcode(ERRCODE_INDEX_CORRUPTED),
3422 : : errmsg("internal page block %u in index \"%s\" is half-dead",
3423 : : blocknum, RelationGetRelationName(state->rel)),
3424 : : errhint("This can be caused by an interrupted VACUUM in version 9.3 or older, before upgrade. Please REINDEX it.")));
3425 : :
3426 : : /*
3427 : : * Check that internal pages have no garbage items, and that no page has
3428 : : * an invalid combination of deletion-related page level flags
3429 : : */
3204 andres@anarazel.de 3430 [ + + - + ]:CBC 17982 : if (!P_ISLEAF(opaque) && P_HAS_GARBAGE(opaque))
3204 andres@anarazel.de 3431 [ # # ]:UBC 0 : ereport(ERROR,
3432 : : (errcode(ERRCODE_INDEX_CORRUPTED),
3433 : : errmsg_internal("internal page block %u in index \"%s\" has garbage items",
3434 : : blocknum, RelationGetRelationName(state->rel))));
3435 : :
1756 pg@bowt.ie 3436 [ - + - - ]:CBC 17982 : if (P_HAS_FULLXID(opaque) && !P_ISDELETED(opaque))
1756 pg@bowt.ie 3437 [ # # ]:UBC 0 : ereport(ERROR,
3438 : : (errcode(ERRCODE_INDEX_CORRUPTED),
3439 : : errmsg_internal("full transaction id page flag appears in non-deleted block %u in index \"%s\"",
3440 : : blocknum, RelationGetRelationName(state->rel))));
3441 : :
1756 pg@bowt.ie 3442 [ - + - - ]:CBC 17982 : if (P_ISDELETED(opaque) && P_ISHALFDEAD(opaque))
1756 pg@bowt.ie 3443 [ # # ]:UBC 0 : ereport(ERROR,
3444 : : (errcode(ERRCODE_INDEX_CORRUPTED),
3445 : : errmsg_internal("deleted page block %u in index \"%s\" is half-dead",
3446 : : blocknum, RelationGetRelationName(state->rel))));
3447 : :
3204 andres@anarazel.de 3448 :CBC 17982 : return page;
3449 : : }
3450 : :
3451 : : /*
3452 : : * _bt_mkscankey() wrapper that automatically prevents insertion scankey from
3453 : : * being considered greater than the pivot tuple that its values originated
3454 : : * from (or some other identical pivot tuple) in the common case where there
3455 : : * are truncated/minus infinity attributes. Without this extra step, there
3456 : : * are forms of corruption that amcheck could theoretically fail to report.
3457 : : *
3458 : : * For example, invariant_g_offset() might miss a cross-page invariant failure
3459 : : * on an internal level if the scankey built from the first item on the
3460 : : * target's right sibling page happened to be equal to (not greater than) the
3461 : : * last item on target page. The !backward tiebreaker in _bt_compare() might
3462 : : * otherwise cause amcheck to assume (rather than actually verify) that the
3463 : : * scankey is greater.
3464 : : */
3465 : : static inline BTScanInsert
920 pg@bowt.ie 3466 : 2061403 : bt_mkscankey_pivotsearch(Relation rel, IndexTuple itup)
3467 : : {
3468 : : BTScanInsert skey;
3469 : :
3470 : 2061403 : skey = _bt_mkscankey(rel, itup);
739 3471 : 2061403 : skey->backward = true;
3472 : :
2463 3473 : 2061403 : return skey;
3474 : : }
3475 : :
3476 : : /*
3477 : : * PageGetItemId() wrapper that validates returned line pointer.
3478 : : *
3479 : : * Buffer page/page item access macros generally trust that line pointers are
3480 : : * not corrupt, which might cause problems for verification itself. For
3481 : : * example, there is no bounds checking in PageGetItem(). Passing it a
3482 : : * corrupt line pointer can cause it to return a tuple/pointer that is unsafe
3483 : : * to dereference.
3484 : : *
3485 : : * Validating line pointers before tuples avoids undefined behavior and
3486 : : * assertion failures with corrupt indexes, making the verification process
3487 : : * more robust and predictable.
3488 : : */
3489 : : static ItemId
2427 3490 : 4723003 : PageGetItemIdCareful(BtreeCheckState *state, BlockNumber block, Page page,
3491 : : OffsetNumber offset)
3492 : : {
3493 : 4723003 : ItemId itemid = PageGetItemId(page, offset);
3494 : :
3495 [ - + ]: 4723003 : if (ItemIdGetOffset(itemid) + ItemIdGetLength(itemid) >
3496 : : BLCKSZ - MAXALIGN(sizeof(BTPageOpaqueData)))
2427 pg@bowt.ie 3497 [ # # ]:UBC 0 : ereport(ERROR,
3498 : : (errcode(ERRCODE_INDEX_CORRUPTED),
3499 : : errmsg("line pointer points past end of tuple space in index \"%s\"",
3500 : : RelationGetRelationName(state->rel)),
3501 : : errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
3502 : : block, offset, ItemIdGetOffset(itemid),
3503 : : ItemIdGetLength(itemid),
3504 : : ItemIdGetFlags(itemid))));
3505 : :
3506 : : /*
3507 : : * Verify that line pointer isn't LP_REDIRECT or LP_UNUSED, since nbtree
3508 : : * never uses either. Verify that line pointer has storage, too, since
3509 : : * even LP_DEAD items should within nbtree.
3510 : : */
2427 pg@bowt.ie 3511 [ + - + - ]:CBC 4723003 : if (ItemIdIsRedirected(itemid) || !ItemIdIsUsed(itemid) ||
3512 [ - + ]: 4723003 : ItemIdGetLength(itemid) == 0)
2427 pg@bowt.ie 3513 [ # # ]:UBC 0 : ereport(ERROR,
3514 : : (errcode(ERRCODE_INDEX_CORRUPTED),
3515 : : errmsg("invalid line pointer storage in index \"%s\"",
3516 : : RelationGetRelationName(state->rel)),
3517 : : errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
3518 : : block, offset, ItemIdGetOffset(itemid),
3519 : : ItemIdGetLength(itemid),
3520 : : ItemIdGetFlags(itemid))));
3521 : :
2427 pg@bowt.ie 3522 :CBC 4723003 : return itemid;
3523 : : }
3524 : :
3525 : : /*
3526 : : * BTreeTupleGetHeapTID() wrapper that enforces that a heap TID is present in
3527 : : * cases where that is mandatory (i.e. for non-pivot tuples)
3528 : : */
3529 : : static inline ItemPointer
2463 3530 : 1860 : BTreeTupleGetHeapTIDCareful(BtreeCheckState *state, IndexTuple itup,
3531 : : bool nonpivot)
3532 : : {
3533 : : ItemPointer htid;
3534 : :
3535 : : /*
3536 : : * Caller determines whether this is supposed to be a pivot or non-pivot
3537 : : * tuple using page type and item offset number. Verify that tuple
3538 : : * metadata agrees with this.
3539 : : */
2120 3540 [ - + ]: 1860 : Assert(state->heapkeyspace);
3541 [ - + - - ]: 1860 : if (BTreeTupleIsPivot(itup) && nonpivot)
2120 pg@bowt.ie 3542 [ # # ]:UBC 0 : ereport(ERROR,
3543 : : (errcode(ERRCODE_INDEX_CORRUPTED),
3544 : : errmsg_internal("block %u or its right sibling block or child block in index \"%s\" has unexpected pivot tuple",
3545 : : state->targetblock,
3546 : : RelationGetRelationName(state->rel))));
3547 : :
2120 pg@bowt.ie 3548 [ + - - + ]:CBC 1860 : if (!BTreeTupleIsPivot(itup) && !nonpivot)
2120 pg@bowt.ie 3549 [ # # ]:UBC 0 : ereport(ERROR,
3550 : : (errcode(ERRCODE_INDEX_CORRUPTED),
3551 : : errmsg_internal("block %u or its right sibling block or child block in index \"%s\" has unexpected non-pivot tuple",
3552 : : state->targetblock,
3553 : : RelationGetRelationName(state->rel))));
3554 : :
2120 pg@bowt.ie 3555 :CBC 1860 : htid = BTreeTupleGetHeapTID(itup);
3556 [ - + - - ]: 1860 : if (!ItemPointerIsValid(htid) && nonpivot)
2463 pg@bowt.ie 3557 [ # # ]:UBC 0 : ereport(ERROR,
3558 : : (errcode(ERRCODE_INDEX_CORRUPTED),
3559 : : errmsg("block %u or its right sibling block or child block in index \"%s\" contains non-pivot tuple that lacks a heap TID",
3560 : : state->targetblock,
3561 : : RelationGetRelationName(state->rel))));
3562 : :
2120 pg@bowt.ie 3563 :CBC 1860 : return htid;
3564 : : }
3565 : :
3566 : : /*
3567 : : * Return the "pointed to" TID for itup, which is used to generate a
3568 : : * descriptive error message. itup must be a "data item" tuple (it wouldn't
3569 : : * make much sense to call here with a high key tuple, since there won't be a
3570 : : * valid downlink/block number to display).
3571 : : *
3572 : : * Returns either a heap TID (which will be the first heap TID in posting list
3573 : : * if itup is posting list tuple), or a TID that contains downlink block
3574 : : * number, plus some encoded metadata (e.g., the number of attributes present
3575 : : * in itup).
3576 : : */
3577 : : static inline ItemPointer
3578 : 6 : BTreeTupleGetPointsToTID(IndexTuple itup)
3579 : : {
3580 : : /*
3581 : : * Rely on the assumption that !heapkeyspace internal page data items will
3582 : : * correctly return TID with downlink here -- BTreeTupleGetHeapTID() won't
3583 : : * recognize it as a pivot tuple, but everything still works out because
3584 : : * the t_tid field is still returned
3585 : : */
3586 [ + + ]: 6 : if (!BTreeTupleIsPivot(itup))
3587 : 4 : return BTreeTupleGetHeapTID(itup);
3588 : :
3589 : : /* Pivot tuple returns TID with downlink block (heapkeyspace variant) */
3590 : 2 : return &itup->t_tid;
3591 : : }
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